granulocyte mech to helminth infections

Review Article

Granulocytes: effector cells or immunomodulators in the immune

response to helminth infection?

E. T. CADMAN & R. A. LAWRENCE

Royal Veterinary College, Royal College Street, London, UK

SUMMARY

Granulocytes are effector cells in defence against helminthinfections. We review the current evidence for the role ofgranulocytes in protective immunity against different hel-minth infections and note that for each parasite species therole of granulocytes as effector cells can vary. Emerging evi-dence also points to granulocytes as immunomodulatorycells able to produce many cytokines, chemokines and modu-latory factors which can bias the immune response in aparticular direction. Thus, the role of granulocytes in animmunomodulatory context is discussed including the mostrecent data that points to an important role for basophilsunder this guise.

Keywords animal model, basophils, eosinophil, innate immu-nity, mast cell, neutrophil

Granulocytes are activated during helminth infection andhave long been known to act as immune effector cells.In vitro granulocyte-mediated immunity against helminthscan be achieved by antibody-dependent cell-mediatedcytotoxicity (ADCC): antibody binds Fc receptor (FcR)on the cell surface and this initiates cell degranulationand extrusion of toxic granule contents onto the parasite.In vivo alterations in gut physiology and mucus produc-tion are also important granulocyte-mediated effectormechanisms against gut-dwelling helminths. Neutrophilsare the only granulocytes efficient at phagocytosis andthey can engulf and kill micro-organisms by generationof reactive oxygen intermediates in phagolysosomes.However, helminths are too large for phagocytosis andas a consequence the role of neutrophils in helminth-driven effector mechanisms has been overlooked untilrecently.

Over the last decade a more complex picture of therole of granulocytes has begun to emerge. These cellsare now known to act both as initiators of particularimmune response pathways and as regulators of ongoingresponses (Table 1). Eosinophils, mast cells and mostrecently basophils have been mooted as innate cellsresponsible for initiation of Th2 generation. Indeedthese granulocytes can be rapidly recruited to sites ofinfection and draining lymph nodes (dLN) where theyproduce IL-4 and ⁄ or IL-13. Furthermore, basophils canproduce thymic stromal lymphopoietin (TSLP), whichis known to bias the response to Th2. Granulocytes canalso produce ‘alarmins’ which are structurally diverseproteins that are rapidly released following pathogenchallenge and ⁄ or cell death. Alarmins act as chemo-attractants and provide maturation signals for antigenpresenting cells such as DC. They include defensins(neutrophils), cathelicidins (neutrophils and mast cells),high-mobility group box protein 1 and the RNAseeosinophil-derived neurotoxin (EDN) (eosinophils)[reviewed in Ref. (1)].

Correspondence: Rachel A. Lawrence, Royal Veterinary College,Royal College Street, London NW1 0TU, UK (e-mail:[email protected]).Disclosures: NoneReceived: 5 June 2009Accepted for publication: 22 June 2009

Parasite Immunology, 2010, 32, 1–19 DOI: 10.1111/j.1365-3024.2009.01147.x

� 2010 Blackwell Publishing Ltd 1

EOSINOPHILS

In healthy individuals, eosinophils make up only 2–5% ofperipheral white blood cells. However, during activeparasitic helminth infection the proportion of eosinophilsin the blood can reach 40% (2). Together with high IgElevels and mastocytosis, eosinophilia is considered to beone of the cardinal features of parasitic helminth infection.Eosinophils are also well-known for their role in asthmaand other allergic diseases of the respiratory system, andthey play a prominent role in gastrointestinal (GI) disor-ders such as eosinophilic oesophagitis (EE), eosinophilicgastritis, inflammatory bowel disease and gastro-oesopha-geal reflux disease [reviewed in Ref. (3)].

Eosinophils have bi-lobed nuclei and three distinct cyto-plasmic granules: eosinophil-specific granules, which have acrystalloid electron-dense core; primary granules, whichhave no crystalloid core and develop early in maturation;and smaller granules, which contain enzymes such asarylsulfatase. Eosinophils also contain lipid bodies, whichcontribute to the formation of eicanosoid mediators. Foureosinophil-specific toxic proteins are stored in granules,major basic protein-1 (MBP-1), eosinophil peroxidase(EPO), EDN and eosinophil cationic protein (ECP). MBP,EPO and ECP are potent helminth toxins, MBP can inducehistamine release from mast cells, while both EDN andECP can act as ribonucleases (4,5). Granules also contain anumber of cytokines and chemokines as preformed proteins,such as IL-4 and IL-13, which can be rapidly and selectivelyreleased. Primary granules contain Charcot-Leyden crystals(CLC) protein also known as galectin-10 (6).

Eosinophils are capable of piecemeal degranulation, allow-ing selective release of granule proteins in a process mediatedby eosinophil sombrero vesicles (4,7). Degranulation is trig-gered by FcRs recognizing antibody-bound antigen; severalcytokines including IL-3, IL-5, granulocyte macrophage col-ony stimulating factor (GM-CSF), TNF, IFN-b, and plateletactivating factor (PAF) can both enhance, or directly triggerthis process. Human eosinophils express FccRI, FccRIIa,FccRIIb, FccRIII, FceRII and FcaR. Interestingly, mouseeosinophils are fundamentally different from human eosin-ophils in that they do not express the high-affinity IgE FcR,FceRI, and therefore do not degranulate as readily. This hasresulted in some debate as to the suitability of the mouse as amodel for the study of human eosinophil biology. The recentdevelopment of an IL-5 ⁄ eotaxin-2 transgenic mouse in whichextensive eosinophil degranulation accompanies an asthmamodel of pathology should help to clarify this aspect ofeosinophil function (8).

Eosinophils develop in the bone marrow, and theirgrowth is promoted by IL-5, IL-3 and GM-CSF (9). Thesecytokines induce the transcription factor, GATA-1, which

is essential for eosinophil development (10). PU.1 andmembers of the C ⁄ EBP family are also involved in eosino-phil development (11). Release of eosinophils from thebone marrow into the peripheral blood circulation is medi-ated by IL-5 (12) and eosinophils are then recruited to thetissues by the chemokines eotaxin-1 (CCL11), eotaxin-2(CCL24) and eotaxin-3 (CCL26), which bind to the recep-tor CCR3 [reviewed in (13)]. Eotaxin-1, IL-5 and RAN-TES are the primary molecules involved in recruitment ofeosinophils to the lung (14,15). Eotaxin-3 is upregulatedin GI-tract disorders such as EE (16) and eotaxin-1 is alsoimportant in homing to the GI tract (17). Some helminths,for example, Necator americanus are able to specificallycleave eotaxin to inhibit the recruitment of eosinophils tothe infection site (18).

Eosinophils as effector cells in helminth infections

The role of eosinophils as effector cells has been difficultto study during human helminthic infection, and conse-quently, the majority of studies to date, have dissected therole of eosinophils in animal models of disease.

In human filariasis, a rare clinical manifestation is tropi-cal pulmonary eosinophilia (TPE), where asthma-likesymptoms are caused by filarial infection of Brugia malayior Wuchereria bancrofti. Microfilariae die in the lungs andinduce an inflammatory response. The pathology of TPEhas been associated with heightened levels of EDN in bothbroncho-alveolar lavage fluid and serum, which damagesthe lung epithelium through its RNase activity (19).In vitro the eosinophil granule proteins, MBP, EPO, EDNand ECP have all been shown to kill Brugia spp. microfila-riae (20). However, in in vivo filarial-mouse models, therequirement for eosinophils and the eosinophil granuleproteins EPO and MBP in clearance of parasites dependsupon the parasite species, the parasite stage and whetherthe response is an innate response to primary infection oran adaptive response to secondary infection. Additionally,the results come from multiple different model systemswhich may not always be directly comparable, for example,studies have used Onchocerca sp. L3 in a chamber model,Brugia sp. in a nonnatural intra-peritoneal site or Litomos-oides sigmodontis which invades the thoracic cavity unlikehuman infections.

In models of brugian filariasis, the presence of eosin-ophils is necessary for killing of primary, but not second-ary infections for both B. pahangi L3 and B. malayimicrofilariae (21,22). Interestingly the eosinophil-mediatedclearance of primary B. pahangi L3 infection was notdependent on the presence of either EPO or MBP (23).However, the clearance of primary but not secondaryB. malayi microfilarial infections, was associated with high

E. T. Cadman & R. A. Lawrence Parasite Immunology

2 � 2010 Blackwell Publishing Ltd, Parasite Immunology, 32, 1–19

levels of serum EPO. This suggests that during primary,but not secondary, infection eosinophils degranulate in theblood (22). In secondary B. malayi microfilariae infectionsdegranulation does occur in the lung and MBP can beseen on the surface of the airway epithelial cells. Thisdegranulation is associated with airway hyper-responsive-ness (24) reminiscent of the eosinophil-associated remodel-ling of the lung that occurs in asthma models (25,26).

In contrast to work with Brugia sp., eosinophils increaseclearance of both primary and secondary infections ofOnchocerca volvulus L3. Eosinophils and serum IgE arerequired for the induction of immunity to a challenge L3infection although in both primary and secondary infec-tion eosinophil-mediated killing is independent of EPO(27). Death of onchocercal microfilariae following amocar-zine treatment is, however, associated with eosinophildegranulation and ECP deposition (28).

In the closely related filarial mouse model, L. sigmodontis,eosinophils can play a protective role in both primary andsecondary infection. However, their role varies accordingto the mouse strain used. Over-expression of IL-5 insusceptible BALB ⁄ c mice, greatly reduced adult wormrecovery from a primary L3 infection and the wormsbecome surrounded by deposits of MBP. In nonpermissivemouse strains (C57Bl ⁄ 6), IL-5 is not necessary for controlof parasite recovery during primary infection, but doesplay an important role in protective immunity followingimmunization (29). In contrast in another nonpermissivestrain, deficiency in either EPO or MBP enhancedL. sigmodontis L3 establishment although the nematodesstill do not survive long enough to reach patency. Thisstudy also revealed an interaction between eosinophil gran-ule proteins and the cytokine responses of macrophagesand CD4+ T cells, which could play a role in worm estab-lishment (30). For example IL-10 production is elevated inthe absence of EPO or MBP, while IL-5 production iselevated in the absence of EPO alone. IL-4 production isreduced in both infected and noninfected EPO or MBP) ⁄ )

mice. Indeed the role of eosinophils in primary infection inBALB ⁄ c mice is unlikely to be in ADCC as absence of Bcells does not alter worm recovery. In secondary infectionsB cells are necessary for eosinophil degranulation andtherefore likely play a role in ADCC (31,32).

Purified eosinophil granule proteins can kill Schistosomamansoni schistosomulae (33), and Trichinella spiralis new-born larvae in vitro (34). However, although eosinophiliais induced during infection with S. mansoni, eosinophil-deficient (dblGATA) mice exhibit no obvious defects inthe immune response to this parasite in vivo (35). Indeed,the lack of eosinophils had no effect on worm burden, eggdeposition, granuloma number, granuloma size or fibrosisdetected at weeks 8 or 12 of infection (35). Thus, the main

function of eosinophils in this infection maybe in tissueremodelling and debris clearance following injury (35).

Similarly although Nippostrongylus brasiliensis infectedanimals develop IL-5-dependent eosinophilia, mast-cellhyperplasia and polyclonal IgE, none of these factors playsa role in expulsion of a primary infection (36). Eosinophil-deficient mice (dblGATA) mice exhibit normal expulsionof a primary N. brasiliensis infection. In addition theseeosinophil-less mice have unaltered Th2 responses, basophilaccumulation and IgE production showing that eosinophilsplay little role in these responses during N. brasiliensisinfection (37). In contrast, eosinophils do contribute toexpulsion of secondary N. brasiliensis infections asdblGATA mice depleted of CD4+ T cells have significantlygreater worm burdens than WT mice depleted of CD4+ Tcells (38). Similarly studies with T. spiralis in IL-5) ⁄ ) miceshowed larger worm burdens and slower expulsion insecondary but not primary infections (39).

Eosinophils as modulators of the immune response

In detailed studies of the role of eosinophils duringStrongyloides stercoralis infection, eosinophils emerge aseffectors during primary infection when they degranulateand are directly involved in killing (40,41). In secondaryinfection they play a more immunomodulatory role andtheir presence is required for the initiation of a protectiveIgM-mediated response (40).

The ways in which eosinophils modulate immuneresponses are only beginning to be discovered. Eosinophilscultured in vitro are able to function as antigen-presentingcells and present S. stercoralis antigen to na�ve CD4+ T cells(42). If this also occurs in vivo, eosinophils could amplifyantigen-specific T-cell responses and potentially modulatethe adaptive immune response by expressing either Th1 orTh2 cytokines (42,43). Furthermore, eosinophil granuleproteins themselves have been shown to modify immuneresponses in L. sigmodontis infection (30). MBP-1 and EPOdeficient mice showed increased IL-10 production andEPO) ⁄ ) mice had increased IL-5 production duringL. sigmodontis infection, additionally both knockout strainshad reduced IL-4 production with or without infection (30).Interestingly EDN secretion by eosinophils has recentlybeen shown to induce migration and maturation of DCs, aswell as enhancing Th2 responses via Toll-like receptor(TLR) 2 activation (44). EDN-stimulated splenocytesproduced enhanced levels of IL-5, IL-6, IL-10 and IL-13cytokines, as well as higher levels of IgG1 than IgG2asuggesting that EDN acts as an alarmin that alerts theimmune system for preferential Th2 immune responses.

Eosinophils can also recruit T cells into sites such as thelung through the expression of CCL17 and CCL22 (45).

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� 2010 Blackwell Publishing Ltd, Parasite Immunology, 32, 1–19 3

Indeed eosinophils indirectly affect the development ofrespiratory symptoms through their effects on nerves inthe lung. Eosinophils adhere to parasympathetic nervesvia vascular cell adhesion molecule (VCAM)-1 and inter-cellular adhesion molecule (ICAM)-1 (46), and releasetheir granule proteins including EPO, MBP-1 and leukotri-enes (46,47). MBP-1 blocks inhibitory receptors on nerves,thereby increasing stimulation of airway smooth muscle(48). Substance P, a neuropeptide, can also stimulateeosinophil degranulation (49), providing the potential fora positive feedback loop of nerve activation. Anti-cholin-ergic drugs, which would be expected to decrease nerveexcitation, can in fact increase eosinophil activation anddegranulation, thereby exacerbating asthma-like symptoms(50). Eosinophils can even influence the morphology ofnerves by inducing neurite retraction (51).

Thus, although the role of eosinophils as secretors ofhelminthotoxic molecules has been known for some time,the advent of mouse strains deficient in particular eosino-phil granule proteins has advanced our understanding ofthe function of eosinophils and their associated granuleproteins. In the next few years, the role of eosinophils asimmunological modulators will become more apparent.

MAST CELLS

Mastocytosis is intimately associated with helminth infec-tions particularly those that live in the intestinal tract.Mast cells are distributed throughout the connective tis-sues and lie adjacent to blood and lymphatic vessels,nerves and epithelial surfaces. Mast cells are most closelyrelated to basophils, with which they share a common pro-genitor (52). They are derived from CD34+ progenitorcells in the bone marrow, and unlike other granulocytes,mast cells mature in the periphery following interactionwith stem cell factor ⁄ c-kit ligand (SCF) (53). In fact, SCFis an absolute requirement for mast cell development andmice lacking c-kit function (W ⁄ Wv) do not produce thesecells (54,55). Despite upregulation in many helminth dis-eases they are not always necessary for clearance (seebelow). However, the protective response to T. spiralisinfection is notably highly dependent on mast cells.

The classical function of mast cells is as end-stage effectorcells, releasing proteases and inflammatory proteins such ashistamine during degranulation. Their granules also containpreformed cytokines e.g. IL-4 and IL-13 (5). Mast cellsexpress the high affinity IgE receptor, FceRI, which whencross-linked by antigen, triggers degranulation (56). Theyare generally divided into two types, mucosal mast cells(MMC) and connective tissue mast cells (CTMC), definedby anatomic location, granule contents, and function (57).MMC in mice express MMC protease-1 (mMCP-1) (rMCP-

II in rats) and tryptase, they are dependent on T cells andare located predominantly in the lung and nasal cavity andintestinal epithelia (58–60). MMC are shorter lived thanCTMC (<40 days), have more FceR and also have cytoplas-mic IgE. CTMC produce tryptase, chymotryptase, heparinand histamine, are T-cell-independent and are predomi-nantly in the skin and sub-epithelial mucosa of the respira-tory and intestinal tracts (57,61). Both cells producearachadonic acid metabolites although the amount and typevaries between the two types of mast cells.

Mast cells are recruited to the small intestine by the in-tegrin a4b7 (62) and to the lungs by both a4b7 and a4b1(63). For small intestinal homing, a4b7 binds the ligandMAdCAM-1, however for homing to the lung the a4 inte-grins bind VCAM-1. Because of the importance of a4b7for small intestine mast cell responses, protection againstT. spiralis, but not T. muris (which colonizes the largeintestine) is delayed in b7-integrin deficient mice (62,64).Other chemotactic factors for mast cells include SCF,which in addition to its role as a growth factor can act asa chemotactic factor for mast cell exit from the bone mar-row (65). Cytokines such as TNFa, IL-8 and IL-4, chemo-kine receptors such as CCR3 and CXCR3 and antigencross-linking IgE are also chemotactic for mast cells (66–68). Monomeric IgE in the absence of antigen can pro-mote both mast cell survival and the release of mast cellcytokines (69–72).

Mast cell products

IgE and antigen triggers degranulation of mast cells, andin mice this is also achieved by IgG1 binding to FccRIII[reviewed in Ref. (73)]. It was previously thought thathelminths suppress allergic responses by stimulating largequantities of polyclonal IgE which saturate the high affin-ity receptor on mast cells [reviewed in Ref. (74)], howeverno correlation between levels of serum IgE and histamineproduction has been demonstrated in helminth-infectedpatients (75). Indeed even small quantities of antigen-spe-cific IgE are sufficient to trigger mast cell degranulation,despite the simultaneous presence of nonspecific IgE (76).Histamine itself further induces mast cell degranulationindirectly by affecting nonmast cell function and both IL-10 and SCF will enhance histamine secretion (77,78).

Mast cells produce a wide array of cytokines, the pro-duction of which can be stimulated by IL-3 and IL-18, inthe absence of IgE cross-linking (79). TLR ligand activa-tion by LPS or peptidoglycan (PGN) leads to differentialcytokine secretion; LPS stimulates TNFa, IL-6, IL-1b andIL-13 while PGN stimulates, IL-4, IL-5, IL-6 and IL-13respectively (80,81). TLR2 and TLR4 ligation alsoenhance degranulation mediated by FceRI (82).



Mast cells also secrete a number of chemoattractantsincluding chemokines and mast cell proteases (83). Indeed,mMCP-6) ⁄ ) mice have defective eosinophil recruitment tothe site of T. spiralis larval infection and this results inreduced larval necrosis (84). Injection of recombinantmMCP-6 (but not the closely related mMCP-7) can inducemigration of neutrophils into the peritoneal cavity of unin-fected mice (85,86). Other secreted proteases such as trans-membrane tryptase (TMT) may increase pathologyfollowing degranulation; TMT can amplify IL-13 produc-tion from T cells and induce tracheal airway hyperrespon-siveness (87). Thus mast cells can influence the activity ofother cells of the immune system by the release of granuleproducts, including cytokines, chemokines and proteases[reviewed in (88)].

Necessity for cytokines in development and effectoractivity of mast cells

Mast cells are important in the immune response to manyhelminth infections, particularly T. spiralis, S. ratti, Heligmo-somoides polygyrus, S. mansoni and Haemonchus contortus(89–94). However, despite upregulation in a number ofhelminth infections, as mentioned above, the role of mastcells in parasite clearance is less critical. Mast cells play animportant role in expulsion of T. spiralis, however, mast cellsare not critical for expulsion of GI parasites such as T. murisor N. brasiliensis (95,96) or for the development of vaccine-induced immunity to S. mansoni in mice (93,97,98).

Much of what is known about mast cells has been dis-covered in humans or mice with particular cytokine defi-ciencies. Indeed the T-cell dependency of some mast cellpopulations is demonstrated by the absence of intraepithe-lial intestinal MMC from humans and mice that have T-cell deficiencies. IL-3, IL-4, IL-9 and IL-10 are all Th2 cellcytokines that are known to influence mast cell develop-ment and phenotype (99,100). The necessity for these cyto-kines in mast cell development has largely been analysedusing mouse models of helminth infection (see below).

A useful tool in analysis of mast cell function has beenthe dependence on mast cells for expulsion of the hel-minth, T. spiralis. Thus, mast-cell deficient W ⁄ Wv mice ormice treated with anti-SCF are unable to expel T. spiralis(68). Mast cell protease-1 is known to be critical in T. spi-ralis clearance, as mMCP-1) ⁄ ) mice have delayed expul-sion and increased deposition of larvae in the muscles(101). The importance of IL-10 in mast cell developmentis demonstrated by a reduction in mast cells and mMCP-1production in the gut leading to delayed expulsion ofT. spiralis in IL-10-deficient mice while muscle larval deathis increased due to increased production of IFN-c (102).Interestingly, the fecundity of N. brasiliensis is increased

SCF presence, although MCP-1 has no effect on N. brasili-ensis infection (103).

IL-3 is necessary for jejunal mast cell hyperplasia duringinfection with Strongyloides venezuelensis (104). In con-junction with SCF, IL-3 also promotes cytoplasmic gran-ule formation in immature mast cells and IL-3 is oftenused to culture mast cells in vitro (105) (despite this how-ever, IL-3) ⁄ ) mice can still expel T. spiralis as efficiently aswild-type mice (68)]. Wild-type mice, but not W ⁄ Wv mice,treated with IL-18 and IL-2, mediate rapid expulsion ofadult S. venezuelensis (as do IL-18 ⁄ IL-2 treated Stat6) ⁄ )

mice) while IL-18) ⁄ ), IL-18Ra) ⁄ ) or Stat6) ⁄ ) mice havedelayed S. venezuelensis expulsion (106). The data suggestan innate IL-18-dependent MMC activation and a Th2cell-dependent (acquired type 2) MMC activation is neces-sary for S. venezuelensis expulsion (106).

The importance of other cytokines for generation ofmastocytosis has also been shown in helminth model sys-tems. Together, IL-9 and SCF promote differentiationtowards the MMC phenotype. IL-9 transgenic mice gener-ate a huge mastocytosis and rapidly expel both T. spiralisand T. muris (107–109). In addition, IL-9) ⁄ ) mice do notdevelop jejunal or large intestinal mastocytosis duringN. brasiliensis or T. muris infection respectively whichdelays expulsion of T. muris. In another system, IL-4and IL-10 together can promote mast cell differentiationin vitro and these cells can rescue impaired immunity toS. venezuelensis in phosphatidylinositol-3 kinase deficientmice, which lack GI mast cells (110).

Some cytokines may have slightly differing roles inhuman and mouse mast cell development, for example, IL-4is a mast cell growth factor in mice (99), while in humansthe evidence is conflicting, although in combination withSCF, IL-4 is now thought to enhance mast cell proliferationand Th2 cytokine expression (111–113). In the absence ofIL-4, mast cells produce TNFa and IL-18. Recently, it hasbeen shown that the source of this IL-4 for mast cell devel-opment may be basophils (see ‘Basophils’ section).

In contrast to the Th2 cytokines, IFN-c suppressesmouse mast cell differentiation and induces apoptosis(114) but promotes survival of human mast cells (115).TNFa (116), IL-6 (111) and nerve growth factor (117) canall promote mast cell development in concert with IL-3.The transcription factors GATA-1 and GATA-2 areinvolved in mast cell development (118,119), as is PU.1(120), which is essential for mast cell generation in thepresence of GATA-2.

Pathology

Although mast cells are important in immune responses tomany helminth parasites, they may also be the cause of



excess pathology during helminth infection. Mice whichlack either mast cells or MCP-1 have reduced intestinalpathology during T. spiralis infection (121). MCP-1degrades occludin, causing impairment of the epithelial-cell barriers and increased mucosal leakiness (122). Othermast cell products such as histamine and prostaglandinshave similar effects on epithelial cell barrier disruption.Interestingly mast cells can prevent establishment ofS. venezuelensis by secreting glycosaminoglycans thatinhibit the adhesion of worms to the epithelial cells (123).

Mast cells and antigen presentation

There is a growing body of evidence linking mast cells tothe function of antigen-presenting cells. Histamine hasbeen shown to improve the uptake of soluble antigens byDCs and the cross-presentation of these antigens on MHCclass I molecules (124). Indeed mast cell histamine, prosta-glandin E2 and TNFa, can act on DC chemokine expres-sion to favour the recruitment of Th2 cells (125).Histamine and IL-3 can also influence the production ofTh1 and Th2 responses through the histamine receptors,H1 and H2, on T cells (126). Indeed mast cells themselvesare able to act as antigen-presenting cells to T cellsin vitro; they can express MHC Class I and II, as well asCD28, CD80 and CD86 (127–130). However, whethermast cells play a role as APC during helminth infectionin vivo is not known.

Stimulation of mast cells by parasite antigens

Relatively few parasite antigens that bind IgE and inducemast cell degranulation have been identified. In N. brasili-ensis, Nb-Ag1, a pharyngeal antigen, (possibly a digestiveenzyme) is known to bind IgE and cause mast cell degran-ulation during primary, secondary and tertiary infection.This response does not occur in IgE) ⁄ ) mice. The IgE islikely to be antigen-specific, as although no anti-Nb-Ag1IgE was detected by ELISA during primary infection,when infected with H. polygyrus there is no degranulationof basophils in response to N. brasiliensis antigen (76).

Inhibition of mast cells by parasite products

The importance of mast cells in immunity to some para-sitic infections is demonstrated by the evolution of para-sitic molecules that combat mast cell products. A. viteaesecretes a protein, ES-62, which can inhibit mast celldegranulation by complexing with TLR4 and PKCa andinducing degradation of PKCa (a regulator of mast cellresponses). The initial peak of calcium mobilization nor-mally triggered by the high affinity Fce receptor is pre-

vented by ES-62, which also selectively inhibits mast cellTNFa, IL-3 and IL-6 but not IL-5 or IL-13 (131).Another nematode, T. suis, expresses a chymotrypsininhibitor which can inhibit chymase (mouse mast cell pro-tease-1, mMCP-1), as well as neutrophil elastase andcathepsin G (132). In contrast, some parasite products,such as the body fluid of the nematode parasite Ascarissuum, appear to promote histamine release (133).

Given the wide array of cytokines, chemokines andother immunomodulatory factors that are produced bymast cells, the classic view of mast cells as simple effectorcells is rapidly changing. We can expect that in the nearfuture more will be learnt of their role in directing anti-helminth immunity either by secretion of stimulatory fac-tors or indeed by playing a part in antigen presentation.

NEUTROPHILS

Neutrophils develop in the bone marrow. They rapidlyaccumulate at the site of an infection, kill invading bacte-ria and regulate the inflammatory response in wound heal-ing and tissue repair. Neutrophils are often the first cellsto be recruited to a site of inflammation, where theyengulf microorganisms by phagocytosis. Once in thephagolysosome, the respiratory burst and formation ofoxidative (reactive oxygen species) and nonoxidative mech-anisms kill and degrade pathogens. Appelberg (134) alsorecently suggested that neutrophils may play a nonphago-cytic role in the transfer of pathogen to local lymph nodes,in Ag presentation and in early T-cell recruitment. Becauseof their predominant function in phagocytosis of micror-ganisms, until recently the role of neutrophils in combat-ing helminth infection has been largely ignored.

Neutrophils highly express Ly-6G (Gr-1), as do a subsetof monocytes (Gr1+ F4 ⁄ 80+ alternately activated macro-phages), DCs and eosinophils. They contain four types ofgranule: azurophil (primary), specific (secondary), gelati-nase (tertiary) and secretory. The primary granules containmyeloperoxidase acid hydrolases, lysozyme, bacterial per-meability-increasing protein, defensins and serine proteases(cathepsin G, neutrophil elastase and proteinase 3). Thesecondary granules contain lactoferrin and lysozyme [seeRef. (135) for a review of neutrophil serine protease biol-ogy].

In 2004, Tsuda et al. (136), proposed three distinct sub-sets of neutrophils (PMN-I, PMN-II and PMN-N) distin-guished as follows: (1) cytokine and chemokineproduction (PMN-I, IL-12 ⁄ CCL3; PMN-II, IL-10 ⁄ CCL2;PMN-N, no cytokine ⁄ chemokine production), (2) macro-phage activation (PMN-I, classically activated macrophag-es; PMN-II, alternatively activated macrophages; PMN-N,no effect on macrophage activation), (3) TLR expression



(PMN-I, TLR2 ⁄ TLR4 ⁄ TLR5 ⁄ TLR8; PMN-II, TLR2 ⁄TLR4 ⁄ TLR7 ⁄ TLR9; PMN-N, TLR2 ⁄ TLR4 ⁄ TLR9) and(4) surface antigen expression (PMN-I, CD49d+CD11b);PMN-II, CD49d) CD11b+; PMN-N, CD49d) CD11b).This is useful as an illustration of the plasticity of neu-trophils, however general use of these terms has not (yet)been adopted.

Recruitment of neutrophils

During helminth infection, as with inflammatory models,neutrophils are the first cells to be recruited. For example,in filarial models in which B. pahangi L3 are injected intothe peritoneal cavity of mice or in the dermis of gerbils,there is an innate peak of neutrophil recruitment at 24 h,however by day 4 post-infection this influx disappears(137,138). In mice even in the absence of T cells, B cells orboth, neutrophils are still recruited. In contrast to neutro-phils, eosinophil recruitment, starts at day 10 and isdependent on the presence of T cells.

In fact during L. sigmodontis filarial infections, neu-trophils have been suggested to play a protective role.IFN-c) ⁄ ) (BALB ⁄ c) mice have a twofold increase in wormrecovery, reduced neutrophilic infiltration and the wormsare less encapsulated in nodules than in wild-type mice.TNF-a, a major neutrophil activation factor is greatlyreduced in IFN-c) ⁄ ) compared to wild-type mice. Further-more neutrophil chemotactic and phagocytic ability isimpaired (139). Similarly, in the absence of IL-5 alone,worm recovery was increased and there were no nodulesaround the worms (140). When IFN-c, in addition to IL-5, was absent the worm recovery was more greatlyenhanced suggesting a synergy between IFN-c and IL-5 ininduction of immune responses. The authors concludedthat higher adult worm counts were mediated by lowerneutrophil recruitment however these doubly-deficientmice had lower neutrophils, macrophages, NK cells, CD4+

cells, reduced phagoctyosis and reduced TNF-a from mac-rophages compared to wild-type mice. Interestingly, highermicrofilarial counts associated with reduced level of accu-mulation of neutrophils in the thoracic cavity were foundin IL-5) ⁄ ) mice, but there was no additional increase inmicrofilariae with the loss of IFN-c, suggesting thatmicrofilariae are not be affected by loss of neutrophilia(140).

In our own studies (Simons et al., in preparation),reduced survival of B. malayi microfilariae in the bloodstream of CBA mice was associated with an early peak(24 h) of blood neutrophilia compared to C57Bl ⁄ 6 mice.In addition, microfilarial, but not adult nematode, survivalin the peritoneal cavity was greatly reduced in the absenceof IL-10 and this was associated with an influx of

neutrophils. However, anti-Gr1 treatment (which com-pletely abrogated neutrophils but did not affect other leu-cocytes) showed that neutrophils were not essential forclearance of primary or secondary infections of intrave-nous microfilariae. In contrast neutrophils have howeverbeen reported to play a role in the clearance of secondaryO. volvulus L3 infections in mice (27).

Recruitment of neutrophils to the site of filarial worminfection may in part be a response to the symbiotic Wol-bachia sp. bacteria contained in these worms. This is evi-denced by the fact that neutrophils accumulate aroundO. volvulus worms (which contain Wolbachia sp.) whileneutrophil accumulation is reduced in infected patientsfollowing doxycycline (DOC) treatment, which killsWolbachia. Interestingly the deer filariae, O. flexuosa whichdoes not contain Wolbachia does not attract neutrophilsaround it. Furthermore, O. volvulus extracts induce TNF-aand IL-8 in monocytes but following treatment with DOCthey no longer induce these cytokines (141).

That neutrophils can be protective against nematodeparasites has been shown most definitively in the Strongy-loides sp. model. Immune serum or purified IgM or IgGcan transfer protective immunity against S. stercoralis L3in mice. The protective IgM response is complement andgranulocyte dependent but ADCC-independent (142). Ifdeoxycholate-solubilized L3 are used to immunize, theprotective response is IgG-dependent in an ADCC-inde-pendent manner (143). In contrast if IgG is raised in miceimmunized with live S. stercoralis L3 (rather than antigen)the response requires complement activation and neu-trophils for killing through an ADCC mechanism. Thus,IgM and IgG antibodies can both be protective againstlarval S. stercoralis, but they recognize different antigensand utilize different killing mechanisms which may or maynot involve neutrophils (144) [granulocytes, most likelyneutrophils, are also crucial in controlling S. ratti in mice(145)]. Importantly, neutrophils are shown to be requiredfor killing S. stercoralis L3 in the diffusion chambermouse model in CXCR2) ⁄ ) mice. These mice are deficientin the IL-8 receptor homologue, have a defect in neutro-phil recruitment and in both innate and adaptive immu-nity to S. stercoralis L3 (41). Later studies showed thatGai2 protein is required for neutrophil recruitment andefficient larval killing of S. stercoralis in mice (146).

Neutrophil modulation of helminth-induced immuneresponses

Neutrophils can also play an immuno-modulatory role inhelminth infections and in some circumstances they candrive the response toward the Th2 phenotype. In N. brasil-iensis infection, Gr1+ cells expressing TGF-b and TNF-a,



transiently enter the dLN at 18 h post-infection. Anti-Gr1+ treatment causes an increase in IFN-c and serumIgG2a together with a systemic bacterial infection (pre-sumably due to carry of bacteria from faecally derivedL3), decreased host survival, reduced Th2 (IL-4 and IL-13) differentiation and serum IgE and delayed wormexpulsion (147). Interestingly, treatment of N. brasiliensisL3 with antibiotic before inoculation eliminated bacteriaand restored the protective Th2 response in anti-Gr1-trea-ted mice. Therefore neutrophils limit inflammation andhost mortality (60–80% mortality if Gr1-treated) generatedby nematode-associated bacterial infection and help toinduce optimal Th2 responses. Indeed during Leishmaniamajor infections in BALB ⁄ c mice neutrophils are a sourceof early IL-4 (148). CCL2 is a chemokine that is knownto attract neutrophils in an endotoxin lung model and toinduce Th2 in a sepsis model (149). It is surprising, inlight of the above results, that although neutrophil infiltra-tion into the lymph node following N. brasiliensis inCCL2) ⁄ ) (MCP-1) ⁄ )) mice is abrogated neither wormrecovery nor egg deposition are not significantly affected.T. muris expulsion is delayed in CCL2) ⁄ ) mice andabsence of CCL2 results in decreased monocytes in thelarge intestine, increased IL-12, lower IL-4, and higherTh1 induction, however the role of neutrophils was notexamined in this study (150).

In mouse models of schistosomiasis there is some evi-dence that neutropenia augments egg-induced granulomaformation, through an increase in Th2 cytokines, howeverthis differs with different genetic mouse strains (151). Neu-trophils may modulate the epithelial cell response toT. spiralis as during infection, epithelial cells produceinterleukin-1b (IL-1b), the neutrophil chemotactic factor,macrophage inflammatory protein-2 (MIP-2), and an IL-1antagonist, type II IL-1 receptor (152). Blocking neutro-phil migration results in reduced levels of epithelial cyto-kine mRNA, suggesting that neutrophil infiltrationstimulates the epithelial cell cytokines.

The role of neutrophils in helminth-induced pathology

In some infections neutrophils have been found to exacer-bate helminth-induced pathology. In a mouse model ofcorneal disease caused by O. volvulus infection, antibodyto PECAM inhibited neutrophil, but not eosinophil,recruitment to the cornea and corneal opacification wassignificantly diminished. In contrast if eosinophil but notneutrophil, infiltration was diminished by antibody toICAM corneal opacification was unchanged (153). TLR2(but not TLR4 or TLR9) is necessary for neutrophil infil-tration and in the absence of TLR2, mice do not developcorneal haze. It is thought that Wolbachia may activate

TLR2 (154). Further evidence supporting the role of neu-trophils in this model is seen in CXCR2) ⁄ ) (homologuefor IL-8) mice in which neutrophil, but not eosinophilrecruitment was significantly impaired and they developonly mild corneal opacification (155). Interestingly Wolba-chia surface protein has been shown to inhibit apoptosisof human neutrophils which may further exacerbatepathology caused by filarial parasites (156).

Counter active immune evasion

Several helminths secrete products that aid neutrophilrecruitment. For example, A. suum and T. canis productsinduce a strong chemotactic response in human neutro-phils, they induce neutrophil shape change, and they inducerapid and strong Ca2+ responses in the cytosol. A. suumproducts also interact with pertussis toxin-sensitive G pro-teins through the IL-8R pathway and induce activationand chemotaxis of neutrophils (157). Necator americanusalso produces a neutrophil recruitment factor Na-ASP-2(158) while B. malayi asparaginyl-transfer RNA synthetaseis an immunodominant antigen that induces chemotaxis ofhuman neutrophils, eosinophils, leukocytes and activatesG-protein-coupled receptors CXCR1 and CXCR2 (159).As yet the evolutionary significance of attracting thesecells is not fully understood.

Other helminths produce factors, which may regulatethe pro-inflammatory action of neutrophils. A protein,gp55, secreted by blood-feeding adult stages of H. contor-tus, but not L3 stages, inhibits neutrophils by binding viaCD11b ⁄ CD18 and reduces their H2O2 production (160).Moyle et al. also identified a neutrophil inhibitory factor(NIF) from Ancyslostoma caninum, which bindsCD11b ⁄ CD18 and there is a homologue in A. ceylanicum(161,162). Fasciola hepatica is known to secrete a factorthat inhibits superoxide output from activated neutrophils(163) and secretory products from L3 of N. brasiliensis(164) also inhibit neutrophil recruitment into the bronc-hoalveolar lavage.

Schistosoma mansoni eggs secrete smCKBP (chemokinesbinding protein) which can bind CXCL8, CCL3 andCX3CL1 (fractalkine), CCL2 (MCP-1) and CCL5 (165).SmCKBP blocks CXCL8 and the infiltration of neutro-phils but it does not block CCL11 (eotaxin)-inducedeosinophilia. Brugia malayi secretes BmSPN2 which waspreviously reported to inhibit human neutrophil elastaseand cathepsin G, however when cloned and sequenced byother workers BmSPN2 was found not to inhibit theseneutrophil proteinases (166,167).

As yet the role of neutrophils in immunity to helminthshas been most thoroughly studied in the filarial modelsof disease, in part driven by the possible induction of



neutrophils by symbiotic bacteria. However, the fact thatso many helminths produce either neutrophil regulatory orinhibitory factors suggests that their importance in protec-tion and ⁄ or modulation of immune responses to a rangeof different helminths is more important than has so farbeen realized.

BASOPHILS

Basophils are rare polymorphonuclear granulocytes inperipheral blood (<1% of the leukocytes). They have baso-philic granules in their cytoplasm, they release histamineand they express high-affinity IgE receptor (FceR1) ontheir surfaces. The level of IgE regulates the amount ofFceR1 on basophils (168). These characteristics are sharedwith mast cells. In contrast to mast cells however, baso-phils are c-kit- and they undergo their full maturation inthe bone marrow before entering the blood; mast cells exitthe bone marrow as progenitors and mature in the tissues.Until the recent discovery that basophils are a source ofTh2 cytokines, basophils were treated as a subset of mastcells.

Basophils are a rich source of IL-4, which can be rap-idly produced in an IgE-dependent or an IgE-independentprocess (169). In addition, basophils produce IL-3 (eitherIgE-dependently or independently) and this IL-3 regulatesboth IL-4 and IL-13 expression. Basophils also make IL-4de novo when activated and release a second peak of IL-4after 4 h. IL-13 is first produced after 24 h (170). The life-span of basophils is several days, whereas mast cells sur-vive for weeks or months, and while mast cells proliferatefollowing maturation, basophils undergo expansion in thebone marrow before their release. Human basophils werethought to be most closely related to eosinophils, and theyare found in the respiratory mucosa in late-phase allergicreactions. They respond to the chemoattractants, RAN-TES, MCP-3, MCP-1 and MIP-1a and are activated todegranulate when a multivalent antigen binds several IgEmolecules. Basophils can also be activated IgE-indepen-dently in response to histamine-releasing factor, MCP-1and MCP-3 (171), and they respond to a variety of agon-ists including fMLP, C5a, C3a, PAF, IL-8, MCP-1,MCP-2, MCP-3, MCP-4, eotaxin, RANTES, MIP-1a,IL-3, IL-5, GM-CSF and nerve growth factor (NGF)which can all enhance chemotaxis and mediator release.Degranulation can be piecemeal or anaphylactic, if IgE-mediated, and upon degranulation, basophils can releasehistamine, chondrotin sulphate, neutral protease, elastase,b-glucoronidase, MBP, cathepsin G-like enzyme, CLC,tryptase, chymase and carboxypeptidase, leukotriene C4,PAI-1, IL-4, IL-13 and MIP-1a (171). Activated basophilsexpress CD63 and interestingly basophils can express

CD40L as well as IL-4 and IL-13 and so can induce Bcells to switch to IgE.

BASOPHILIA DURING INFECTION WITHHELMINTHS

Suprisingly, although covered in many textbooks, there islittle robust data showing basophilia during human hel-minth infections. Indeed a worldwide study of basophiliain different helminth infections showed that IgE andeosinophils were raised in all 668 confirmed helminth-infected patients even if they had concurrent protozoalinfections, while people infected with protozoal infectionsalone or uninfected people did not have raised eosinophilsor IgE. In contrast, basophils were raised in only fourhelminth-infected patients (172).

Falcone et al. (173) however did report basophilia inN. americanus infected patients. Despite this paucity ofreports of raised basophils in human helminth infections,basophils from humans infected with Toxocara canis,O. volvulus, W. bancrofti, Loa loa, S. stercoralis and Schisto-soma sp. all release histamine in response to parasite anti-gens in vitro (171,174–177). Basophils from filarial-infectedpatients have been shown to release more IL-4 per cellthan CD4+ cells and at 100-fold lower antigen concentra-tion (178). Indeed basophils are a major source of IL-4 infilarial patients from Papua New Guinea (PNG). Interest-ingly, basophils preferentially release IL-4 in response toL3 rather than adult or microfilarial homogenate suggest-ing that L3 invasion could initiate Th2 responses (179).

Patients with invasive helminth infections have 100 timesthe normal IgE levels compared to 10 times normal levelsin allergic disorders. Thus, one theory for immunologicalincompetence of helminth-infected individuals and theirinability to remove parasites, is that nonspecific polyclonalstimulation of IgE by parasites and ⁄ or the generation ofautoantibodies blocks the FceR1 and disarms the mastcell ⁄ basophil response (180). However, basophils collectedfrom hookworm-infected people from PNG could only bestimulated to release histamine with the specific hook-worm allergen, calreticulin, or anti-human IgE, and not toa nonspecific antigen, ovalbumin (180).

Despite the apparent lack of basophilia during humanhelminth infection, basophils are highly induced in rodenthelminth models. Ordinarily, basophils are rare in theperipheral blood of rodents, but infection with T. spiralisor N. brasiliensis induces a 50-fold blood basophilia. Thisbasophilia is T-cell dependent and does not occur in athy-mic animals (181). In gerbils, blood basophilia and baso-philic clusters in the bone marrow peak after 2 weeks, andare gone by 4 weeks. T. spiralis infection in rats ⁄ guineapigs leads to a basophilia that occurs 1 week earlier than



eosinophilia (182). Several other helminths induce baso-philia in guinea pigs including Strongyloides, Ascaris, Fas-ciola and Trichostrongylus colubriformis which increasebasophils in bone marrow, small intestine and blood (183).

Do specific helminth antigens induce basophils to stimu-late type 2 responses

It has long been suggested that during invasion, helminth-released proteases induce the predominant type 2responses seen in these infections. Importantly, Sokol et al.(184) recently showed that immunization with the cysteineprotease allergen, papain, activates basophils to initiate atype 2 response. Basophils were transiently recruited to thedLN at day 1, prior to the peak of CD4+ IL-4-producingT cells. Although the mechanism of basophil recruitmentto the dLN is unknown, they do possess CCR1, CCR2and CXCR4, and anti-CD62L prevented recruitment, sug-gesting that they enter via crossing high endothelial ven-ules. These basophils express TSLP, an IL-7-like moleculeprimarily produced by epithelial cells and known to beinvolved in Th2 cell differentiation. In vivo depletion ofeither TSLP, IL-4R or basophils (by anti-FceR1) corre-lated with reduced Th2 responses while mast cell defi-ciency or deficiency in TLR2 ⁄ 4 ⁄ Myd88 did not alter Th2responses to papain. Induction of basophils to release IL-6, IL-4 and TNFa, but not histamine, in vitro was foundto lie within the protease activity of papain (184). Thisshowed that basophils have a vital role in the induction ofTh2 responses to some proteases and basophils may becritical for generation of Th2 responses during helminthinfection. However, it has still to be determined whetherthis induction occurs during the basophil’s transient entryinto the lymph node.

Interestingly chitin, a biopolymer of N-acetyl-b-d-gluco-samine and a component of both parasitic and free-livingnematode egg shells, also induces basophilia. Heligmo-somoides polygyrus egg shells are made up of 5% chitinand chitin is a component of the microfilarial sheath offilarial nematodes. Intranasal administration of chitinleads to accumulation of eosinophils and basophils in thelungs of mice, which peak at days 2–3 and return to basallevels by day 9 (185). Chitin also induces eosinophil accu-mulation and alternately activated macrophages as early as6 h post-infection after i.p. administration. Recruitment ofinnate immune cells to chitin is dependent on the highaffinity receptor for leukotriene B4, BLT1, and macro-phages. Indeed expulsion of S. venezuelensis, but notN. brasiliensis, is prevented in BLT1-deficient mice. Nippo-strongylus brasiliensis infection upregulates Stat6-depen-dent genes such as acidic mammalian chitinase (AMCase),Ym1 and Ym2 (chitinase-3-like proteins). AMCase and

Ym2 are expressed in the lung after 9 days. Mice over-expressing AMCase, or immunization of mice withAMCase (but not Ym2) treated-chitin, causes loss ofthe ability to recruit eosinophils and basophils to eitherthe lung or peritoneum (185). Thus, recognition of chitinelicits tissue infiltration and accumulation of IL-4 ⁄ 13 pro-ducing innate cells that are implicated in helminth andallergic immunity, including alternatively activated macro-phages, eosinophils and basophils. AMCase appears tonegatively regulate chitin-induced innate immuneresponses by degrading chitin and thus decreasing eosino-phil and basophil recruitment.

Helminth antigens that directly stimulate the release ofIL-4 from basophils are sometimes termed ‘super-aller-gens’ (171). For example, during the first weeks of schisto-some infection, the immune response is characterized by aTh1 response to worm antigens; subsequently, when eggsare deposited, the response turns to a Th2 response direc-ted against egg antigen. Th2 cells are not induced inresponse to either single-sex male worm or radiation-atten-uated cercarial infections. Indeed, it is now known that amajor secretory egg glycoprotein antigen, interleukin-4-inducing factor from schistosome eggs (IPSE ⁄ alpha-1),can stimulate human basophils to rapidly produce IL-4,trigger degranulation and release IL-13 and histamine.IPSE induces IL-4 production through an antigen-inde-pendent but nonspecific IgE-dependent manner. SimilarlyEchinococcus multilocularis extracts induce release of IL-4and IL-13 from basophils via an IgE-dependent mecha-nism (186). Both Derp1, host dust mite allergen, andN. americanus secretions stimulate basophils to secrete IL-4 and IL-13, in a non-IgE-specific manner (187). Thus,these helminth antigens may trigger innate IL-4 andinduce early Th2 differentiation (188).

Filarial worms and schistosomes produce a homologueof mammalian translationally controlled tumour protein(TCTP), a calcium-binding protein that directly stimulateshistamine release from basophils (189). However, basophilsfrom filarial patients stimulated with B. malayi extractrelease IL-4 whereas those of uninfected patients do not,which may suggest that the levels of TCTP in extract arenot high (178). The lack of IL-4 from uninfected individu-als in this study also suggests that in filarial infectionbasophils are probably not the primary IL-4 source, thatthe IL-4 release is an antigen-specific response and thatthe response may be IgE-dependent. Similarly, A. viteaeextract in conjunction with sera from infected gerbils canstimulate rat basophil leukaemia cells to degranulate.Adult A. viteae extract is more allergenic than infectivelarval or microfilarial extract, and it has been proposedthat the molecule, cystatin may be the stimulating allergen(190).



MODE OF ACTION OF BASOPHILS INPRIMARY AND SECONDARY RESPONSES

The mode of action of basophils in directing innateimmune responses is just beginning to be unravelled. Theprocesses of induction of Th2 responses are complex andmany cells have overlapping functions. Our current under-standing of these processes is given below.

The initial IL-4 production of basophils can be gener-ated directly in response to parasite allergens (as discussedabove) or in response to IL-3. Hida et al. (191) showedthat the FcR c-chain, a constitutive component of the IL-3 receptor, is required for IL-3-induced IL-4 production inbasophils. Basophils lacking FcRc develop normally andproliferate efficiently in response to IL-3, but are severelyimpaired in IL-3-induced production of IL-4 and in sup-porting Th2 differentiation (191). However, IL-3 is notessential for basophil generation or basophil recruitment.IL-18, in conjunction with IL-3, is also able to induce IL-4, IL-13 and histamine release from basophils (192).Indeed in vivo Yoshimoto treated S. venezuelensis infectedmice with IL-2 plus IL-18, which stimulated CD4+ cells toproduce IL-3 and IL-9, which in turn activated mast cellsto produce mMCP-1, and resulted in tissue accumulationof basophils that could act as major IL-4 producers andinitiators of Th2 responses.

During N. brasiliensis infection, basophils are known toproduce IL-4 and to peak at 10-day post-infection in liver,lung, spleen and blood but they are not found in thelymph nodes (193). In the spleen they accumulate near themarginal zone (194). Basophil expansion in the blood andIL-4 expression is Stat6, Ig-FcR cross-linking and CD4+

cell-independent (38). However, recruitment of basophilsto lung and other tissues is Stat6-independent but highlydependent on activated CD4+ cells (38). Although IL-3and IL-18 together could stimulate basophil IL-4 produc-tion without FcR cross-linking, neutralization of IL-3 orIL-18 during N. brasiliensis infection does not completelyabrogate basophil recruitment or basophil-IL-4 productionrespectively (193). Thus, the exact identification of the sig-nals, for bone marrow release of basophils, CD4+ cell-mediated recruitment of basophils to the lung and IL-4release from basophils have yet to be identified in this sys-tem. It is likely that initially T cells responsive to parasiteantigens produce chemokines ⁄ cytokines, possibly partiallyIL-3-mediated that attract basophils and induce IL-4 pro-duction. The recruitment of basophils during N. brasilien-sis infection may in fact be too late for basophils to biasthe initial response toward Th2, however they are likely tohelp drive newly emerging CD4+ cells to continue theongoing Th2 response by their production of IL-4 (193).Indeed one of the functions of IL-4 is to increase the Ag-

presenting and co-stimulatory potential of DC, thereforebasophil-IL-4 production may also increase Th2 responsesindirectly by maturing DC for optimal Ag presentationand Th2 priming. Basophils also produce IL-5 andincrease eosinophilia during N. brasiliensis infection andthis occurs independently of mast cells and Th2 cells. Theimportance of basophils in protection against N. brasilien-sis infection has recently been highlighted; basophils weredepleted in mice that have no Th2 response (rag) ⁄ ) recon-stituted with IL-4 ⁄ IL-13) ⁄ ) lymphocytes) and worm expul-sion was reduced (194).

Naive T cells require some time to initiate IL-4 produc-tion during a primary immune response, most likelybecause their Il4 genes are initially inaccessible. Newlyactivated T cells make relatively small quantities of IL-4,which may be sufficient for Th2 cell differentiation and Bcell isotype switching to IgE. In contrast, the rapid, easilytriggered, short-lived production of much larger quantitiesof IL-4 (and additional cytokines) by basophils may acti-vate nonimmune cells, such as vascular endothelium,smooth muscle and mucosal epithelial cells, which canmodify their function when stimulated with large amountsof IL-4 to promote the expulsion of enteric nematodes.Basophils are more sensitive than mast cells to FceRIcross-linking, which suggests that basophil IL-4 secretionprecedes mast cell degranulation during worm infection.This pre-exposure to IL-4 sensitizes nonbone marrow-derived cells, such as intestinal cells, to mediators releasedby mast cells that promote rapid expulsion of parasites.Indeed, T. spiralis expulsion requires mast cells, IL-4 orIL-13, and nonbone marrow-derived cells that areIL-4 ⁄ IL-13 responsive. Thus, basophils may be able tocontribute to IL-4-mediated immunity and inflammationduring helminth infection through two distinct mecha-nisms: an IgE-independent mechanism that induces persis-tent production of small amounts of IL-4 and is likelyimportant during primary infection for Th2 differentiationand an IgE-dependent mechanism that rapidly induces thesecretion of large amounts of this cytokine and kick-startsthe secondary immune response (193) (Figure 1).

Several studies have modelled the role of basophils insecondary responses. Khodoun et al. (195) showed thatthe secondary basophil IL-4 response to a T-dependentantigen is much larger and faster than the primaryresponse. During the early phase (<4 h) of a secondaryresponse, basophils, but not mast cells or eosinophils,secrete IL-4. Later in the response (4–72 h) when Ag stim-ulates IgE-FceR1 on the surface, memory T cells alsobecome important (195). Further significance for the needfor basophils in secondary immune responses has beenshown in a more physiological context with Streptococcuspneumoniae. Basophils increased humoral memory



responses by producing IL-4 and IL-6 in a secondaryinfection (196). Basophils trap antigen plus antigen-spe-cific IgE with their FceR and then release IL-4 and IL-6.Basophils not only capture antigen by trapping solubleantigens when Ag-specific IgE binds FceR1 on their sur-face; they can also capture Ag-IgG complexes, particularlyIgG1 complexes (197,198). Basophils are the main sourceof IL-4 and IL-6 in the spleen and bone marrow andbasophil depletion leads to increased sepsis, decreased sur-vival following S. pneumoniae and decreased B-cell prolif-eration and antibody production. Thus, basophils areimportant in the humoral memory response for supportingB-cell proliferation and antibody production in the pres-ence of CD4+ cells through IL-4 and IL-6 production andcell–cell contact (Figure 1). They also induce Th2 differen-tiation, which further helps B cells. Thus the ability ofbasophils to make large amounts of IL-4 following FcRtriggering during secondary helminth infection is likely toallow rapid generation of Th2 responses and consequentworm expulsion.

Regulation of basophils

Interferon regulatory factor 2 (IRF-2) is a transcriptionfactor that controls inflammation by attenuating the sig-nals evoked by spontaneously produced IFN-a ⁄ b (199). Inthe absence of IRF-2 (IRF-2) ⁄ ) mice) Th2 cells are prefer-

entially induced. Interestingly, in na�ve IRF-2) ⁄ ) mice ba-sophils are upregulated in spleen and peripheral blood,(independently of Stat6), there is elevated levels of IgE,increased numbers of T1 ⁄ ST2+ cells, and isolated T cellsproduce more IL-4. Indeed, IRF-2) ⁄ ) macrophages donot produce IL-12 although CPG-activated IRF-2) ⁄ ) DCare unaffected. IRF-2 negatively regulates the signal fromIL-3 that leads to basophil proliferative expansion but notbasophil cytokine production. As mentioned above, IL-3is important for IL-4 production by basophils. IRF-2 doesnot affect bone marrow, suggesting that it acts purely atthe IL-3-dependent level. IL-3 treatment also increasesbasophilia and accelerates Th2 differentiation (200).

Overall these are exciting times in granulocyte biology.The modulation of immune responses by eosinophils, mastcells and neutrophils are beginning to be elucidated. Mostimportantly the basophil is currently centre-stage as a cellthat secretes very large amounts of IL-4 and is necessaryfor promotion of type 2 responses. Further elucidation ofthese pathways will be possible with the identification ofantigens ⁄ allergens that can directly stimulate granulocytesto produce particular cytokines and in this light it will beimportant to identify such antigens that may be able tostimulate basophils to initiate Th2 responses. Furthermorethe future generation of mice that lack basophils willdefinitively elucidate their role in these complex immuneresponses.

Bone marrow

? Basophils

InnateSecondary

?

IL-3

IL-18Parasiteallergen

Memory type 2 CD4+Naïve CD4+

Naïve CD4+

IL-4TSLP

B cell IL-4IL-13

DC

DC

IL-4IL-4 IL-4IL-13

B cell

Type 2 CD4+ IL-6

IL-5 Eosinophilia Blood

Basophil

IgE

IL-4

Basophil IgE

Figure 1 Current model of the role of basophils in generation of type 2 responses. CD4+ cell differentiation and IgE production in innateresponses following direct activation of basophils by parasite antigens or IL-3 or IL-18. In secondary responses basophils produce largeamounts of IL-4 in an IgE-dependent manner further assisting type 2 response generation.



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ACKNOWLEDGEMENTS

We would like to thank Amanda de Mestre for criticalreading of the manuscript and the BBSRC(BB ⁄ D013550 ⁄ 1) for supporting the authors’ work.

REFERENCES

1 Oppenheim JJ & Yang D. Alarmins: chemotactic activators ofimmune responses. Curr Opin Immunol 2005; 17: 359–365.

2 Reimert CM, Fitzsimmons CM, Joseph S, et al. Eosinophilactivity in Schistosoma mansoni infections in vivo and in vitroin relation to plasma cytokine profile pre- and posttreatmentwith praziquantel. Clin Vaccine Immunol 2006; 13: 584–593.

3 Rothenberg ME. Eosinophilic gastrointestinal disorders(EGID). J Allergy Clin Immunol 2004; 113: 11–28.

4 Walsh GM. Eosinophil granule proteins and their role in dis-ease. Curr Opin Hematol 2001; 8: 28–33.

5 Gessner A, Mohrs K & Mohrs M. Mast cells, basophils, andeosinophils acquire constitutive IL-4 and IL-13 transcriptsduring lineage differentiation that are sufficient for rapidcytokine production. J Immunol 2005; 174: 1063–1072.

6 Ackerman SJ, Liu L, Kwatia MA, et al. Charcot-Leyden crys-tal protein (galectin-10) is not a dual function galectin withlysophospholipase activity but binds a lysophospholipase inhi-bitor in a novel structural fashion. J Biol Chem 2002; 277:14859–14868.

7 Melo RCN, Spencer LA, Dvorak AM & Weller PF. Mechan-isms of eosinophil secretion: large vesiculotubular carriersmediate transport and release of granule-derived cytokinesand other proteins. J Leukoc Biol 2008; 83: 229–236.

8 Ochkur SI, Jacobsen EA, Protheroe CA, et al. Coexpressionof IL-5 and eotaxin-2 in mice creates an eosinophil-dependentmodel of respiratory inflammation with characteristics ofsevere asthma. J Immunol 2007; 178: 7879–7889.

9 Tominaga A, Takaki S, Koyama N, et al. Transgenic miceexpressing a B cell growth and differentiation factor gene(interleukin 5) develop eosinophilia and autoantibody produc-tion. J Exp Med 1991; 173: 429–437.

10 Yu C, Cantor AB, Yang H, et al. Targeted deletion of a high-affinity GATA-binding site in the GATA-1 promoter leads toselective loss of the eosinophil lineage in vivo. J Exp Med2002; 195: 1387–1395.

11 Du J, Stankiewicz MJ, Liu Y, et al. Novel combinatorial inter-actions of GATA-1, PU.1, and C ⁄ EBPepsilon isoforms regu-late transcription of the gene encoding eosinophil granulemajor basic protein. J Biol Chem 2002; 277: 43481–43494.

12 Mould AW, Matthaei KI, Young IG & Foster PS. Relation-ship between interleukin-5 and eotaxin in regulating bloodand tissue eosinophilia in mice. J Clin Invest 1997; 99: 1064–1071.

13 Conroy DM & Williams TJ. Eotaxin and the attraction ofeosinophils to the asthmatic lung. Respir Res 2001; 2: 150–156.

14 Gonzalo JA, Lloyd CM, Wen D, et al. The coordinatedaction of CC chemokines in the lung orchestrates allergicinflammation and airway hyperresponsiveness. J Exp Med1998; 188: 157–167.

15 Mould AW, Ramsay AJ, Matthaei KI, Young IG, RothenbergME & Foster PS. The effect of IL-5 and eotaxin expression inthe lung on eosinophil trafficking and degranulation and the

induction of bronchial hyperreactivity. J Immunol 2000; 164:2142–2150.

16 Swoger JM, Weiler CR & Arora AS. Eosinophilic esophagitis:is it all allergies? Mayo Clin Proc 2007; 82: 1541–1549.

17 Rothenberg ME, Mishra A, Brandt EB & Hogan SP. Gastro-intestinal eosinophils. Immunol Rev 2001; 179: 139–155.

18 Culley FJ, Brown A, Conroy DM, Sabroe I, Pritchard DI &Williams TJ. Eotaxin is specifically cleaved by hookwormmetalloproteases preventing its action in vitro and in vivo.J Immunol 2000; 165: 6447–6453.

19 O’Bryan L, Pinkston P, Kumaraswami V, et al. Localizedeosinophil degranulation mediates disease in tropical pulmon-ary eosinophilia. Infect Immun 2003; 71: 1337–1342.

20 Hamann KJ, Gleich GJ, Checkel JL, Loegering DA, McCallJW & Barker RL. In vitro killing of microfilariae of Brugiapahangi and Brugia malayi by eosinophil granule proteins.J Immunol 1990; 144: 3166–3173.

21 Ramalingam T, Ganley-Leal L, Porte P & Rajan TV.Impaired clearance of primary but not secondary Brugiainfections in IL-5 deficient mice. Exp Parasitol 2003; 105:131–139.

22 Simons JE, Rothenberg ME & Lawrence RA. Eotaxin-1-regu-lated eosinophils have a critical role in innate immunityagainst experimental Brugia malayi infection. Eur J Immunol2005; 35: 189–197.

23 Ramalingam T, Porte P, Lee J & Rajan TV. Eosinophils, butnot eosinophil peroxidase or major basic protein, are impor-tant for host protection in experimental Brugia pahangi infec-tion. Infect Immun 2005; 73: 8442–8443.

24 Hall LR, Mehlotra RK, Higgins AW, Haxhiu MA & Pearl-man E. An essential role for interleukin-5 and eosinophils inhelminth-induced airway hyperresponsiveness. Infect Immun1998; 66: 4425–4430.

25 Lee JJ, Dimina D, Macias MP, et al. Defining a link withasthma in mice congenitally deficient in eosinophils. Science2004; 305: 1773–1776.

26 Humbles AA, Lloyd CM, McMillan SJ, et al. A critical rolefor eosinophils in allergic airways remodeling. Science 2004;305: 1776–1779.

27 Abraham D, Leon O, Schnyder-Candrian S, et al. Immuno-globulin E and eosinophil-dependent protective immunity tolarval Onchocerca volvulus in mice immunized with irradiatedlarvae. Infect Immun 2004; 72: 810–817.

28 Gutierrez-Pena EJ, Knab J & Buttner DW. Immunoelectronmicroscopic evidence for release of eosinophil granule matrixprotein onto microfilariae of Onchocerca volvulus in the skinafter exposure to amocarzine. Parasitol Res 1998; 84: 607–615.

29 Le Goff L, Loke P, Ali HF, Taylor DW & Allen JE. Interleu-kin-5 is essential for vaccine-mediated immunity but notinnate resistance to a filarial parasite. Infect Immun 2000; 68:2513–2517.

30 Specht S, Saeftel M, Arndt M, et al. Lack of eosinophilperoxidase or major basic protein impairs defense againstmurine filarial infection. Infect Immun 2006; 74: 5236–5243.

31 Martin C, Saeftel M, Vuong PN, et al. B-cell deficiency sup-presses vaccine-induced protection against murine filariasisbut does not increase the recovery rate for primary infection.Infect Immun 2001; 69: 7067–7073.

32 Martin C, Le Goff L, Ungeheuer MN, Vuong PN & Bain O.Drastic reduction of a filarial infection in eosinophilic inter-leukin-5 transgenic mice. Infect Immun 2000; 68: 3651–3656.



33 McLaren DJ, McKean JR, Olsson I, Venges P & Kay AB.Morphological studies on the killing of schistosomula ofSchistosoma mansoni by human eosinophil and neutrophilcationic proteins in vitro. Parasite Immunol 1981; 3: 359–373.

34 Hamann KJ, Barker RL, Loegering DA & Gleich GJ. Com-parative toxicity of purified human eosinophil granule pro-teins for newborn larvae of Trichinella spiralis. J Parasitol1987; 73: 523–529.

35 Swartz JM, Dyer KD, Cheever AW, et al. Schistosoma man-soni infection in eosinophil lineage-ablated mice. Blood 2006;108: 2420–2427.

36 Lawrence RA, Gray CA, Osborne J & Maizels RM. Nippos-trongylus brasiliensis: cytokine responses and nematode expul-sion in normal and IL-4-deficient mice. Exp Parasitol 1996;84: 65–73.

37 Knott ML, Matthaei KI, Giacomin PR, Wang H, Foster PS& Dent LA. Impaired resistance in early secondary Nippos-trongylus brasiliensis infections in mice with defective eosino-philopoeisis. Int J Parasitol 2007; 37: 1367–1378.

38 Voehringer D, Shinkai K & Locksley RM. Type 2 immunityreflects orchestrated recruitment of cells committed to IL-4production. Immunity 2004; 20: 267–277.

39 Vallance BA, Matthaei KI, Sanovic S, Young IG & CollinsSM. Interleukin-5 deficient mice exhibit impaired hostdefence against challenge Trichinella spiralis infections. Para-site Immunol 2000; 22: 487–492.

40 Herbert DR, Lee JJ, Lee NA, Nolan TJ, Schad GA & Abra-ham D. Role of IL-5 in innate and adaptive immunity to lar-val Strongyloides stercoralis in mice. J Immunol 2000; 165:4544–4551.

41 Galioto AM, Hess JA, Nolan TJ, Schad GA, Lee JJ & Abra-ham D. Role of eosinophils and neutrophils in innate andadaptive protective immunity to larval Strongyloides stercora-lis in mice. Infect Immun 2006; 74: 5730–5738.

42 Padigel UM, Lee JJ, Nolan TJ, Schad GA & Abraham D.Eosinophils can function as antigen-presenting cells to induceprimary and secondary immune responses to Strongyloidesstercoralis. Infect Immun 2006; 74: 3232–3238.

43 Liu LY, Bates ME, Jarjour NN, Busse WW, Bertics PJ &Kelly EA. Generation of Th1 and Th2 chemokines by humaneosinophils: evidence for a critical role of TNF-alpha. JImmunol 2007; 179: 4840–4848.

44 Yang D, Chen Q, Su SB, et al. Eosinophil-derived neurotoxinacts as an alarmin to activate the TLR2-MyD88 signal path-way in dendritic cells and enhances Th2 immune responses. JExp Med 2008; 205: 79–90.

45 Jacobsen EA, Ochkur SI, Pero RS, et al. Allergic pulmonaryinflammation in mice is dependent on eosinophil-inducedrecruitment of effector T cells. J Exp Med 2008; 205: 699–710.

46 Sawatzky DA, Kingham PJ, Court E, et al. Eosinophil adhe-sion to cholinergic nerves via ICAM-1 and VCAM-1 andassociated eosinophil degranulation. Am J Physiol Lung CellMol Physiol 2002; 282: L1279–L1288.

47 Jacoby DB, Costello RM & Fryer AD. Eosinophil recruit-ment to the airway nerves. J Allergy Clin Immunol 2001; 107:211–218.

48 Evans CM, Fryer AD, Jacoby DB, Gleich GJ & Costello RW.Pretreatment with antibody to eosinophil major basic proteinprevents hyperresponsiveness by protecting neuronal M2 mus-carinic receptors in antigen-challenged guinea pigs. J ClinInvest 1997; 100: 2254–2262.

49 Evans CM, Belmonte KE, Costello RW, Jacoby DB, GleichGJ & Fryer AD. Substance P-induced airway hyperreactivityis mediated by neuronal M(2) receptor dysfunction. Am JPhysiol Lung Cell Mol Physiol 2000; 279: L477–L486.

50 Verbout NG, Lorton JK, Jacoby DB & Fryer AD. Atropinepretreatment enhances airway hyperreactivity in antigen-challenged guinea pigs through an eosinophil-dependentmechanism. Am J Physiol Lung Cell Mol Physiol 2007; 292:L1126–L1135.

51 Kingham PJ, McLean WG, Walsh MT, Fryer AD, Gleich GJ& Costello RW. Effects of eosinophils on nerve cell morphol-ogy and development: the role of reactive oxygen species andp38 MAP kinase. Am J Physiol Lung Cell Mol Physiol 2003;285: L915–L924.

52 Hallgren J & Gurish MF. Pathways of murine mast cell devel-opment and trafficking: tracking the roots and routes of themast cell. Immunol Rev 2007; 217: 8–18.

53 Okayama Y & Kawakami T. Development, migration, andsurvival of mast cells. Immunol Res 2006; 34: 97–115.

54 Kitamura Y, Go S & Hatanaka K. Decrease of mast cells inW ⁄ Wv mice and their increase by bone marrow transplanta-tion. Blood 1978; 52: 447–452.

55 Alexander WS, Lyman SD & Wagner EF. Expression of func-tional c-kit receptors rescues the genetic defect of W mutantmast cells. EMBO J 1991; 10: 3683–3691.

56 Isersky C, Taurog JD, Poy G & Metzger H. Triggering of cul-tured neoplastic mast cells by antibodies to the receptor forIgE. J Immunol 1978; 121: 549–558.

57 Irani AA, Schechter NM, Craig SS, DeBlois G & SchwartzLB. Two types of human mast cells that have distinct neutralprotease compositions. Proc Natl Acad Sci USA 1986; 83:4464–4468.

58 Ruitenberg EJ & Elgersma A. Absence of intestinal mast cellresponse in congenitally athymic mice during Trichinella spira-lis infection. Nature 1976; 264: 258–260.

59 Newlands GF, Gibson S, Knox DP, Grencis R, Wakelin D &Miller HR. Characterization and mast cell origin of a chymo-trypsin-like proteinase isolated from intestines of miceinfected with Trichinella spiralis. Immunology 1987; 62: 629–634.

60 Miller HR, Huntley JF, Newlands GF, Mackellar A, LammasDA & Wakelin D. Granule proteinases define mast cell het-erogeneity in the serosa and the gastrointestinal mucosa ofthe mouse. Immunology 1988; 65: 559–566.

61 Keller R, Hess MW & Riley JF. Mast cells in the skin of nor-mal, hairless and athymic mice. Experientia 1976; 32: 171–172.

62 Gurish MF, Tao H, Abonia JP, et al. Intestinal mast cell pro-genitors require CD49dbeta7 (alpha4beta7 integrin) for tis-sue-specific homing. J Exp Med 2001; 194: 1243–1252.

63 Abonia JP, Hallgren J, Jones T, et al. Alpha-4 integrins andVCAM-1, but not MAdCAM-1, are essential for recruitmentof mast cell progenitors to the inflamed lung. Blood 2006;108: 1588–1594.

64 Artis D, Humphreys NE, Potten CS, et al. Beta7 integrin-deficient mice: delayed leukocyte recruitment and attenuatedprotective immunity in the small intestine during enteric hel-minth infection. Eur J Immunol 2000; 30: 1656–1664.

65 Pennock JL & Grencis RK. In vivo exit of c-kit+ ⁄ CD49-d(hi) ⁄ beta7+ mucosal mast cell precursors from the bonemarrow following infection with the intestinal nematode Tri-chinella spiralis. Blood 2004; 103: 2655–2660.



66 Romagnani P, De Paulis A, Beltrame C, et al. Tryptase-chy-mase double-positive human mast cells express the eotaxinreceptor CCR3 and are attracted by CCR3-binding chemo-kines. Am J Pathol 1999; 155: 1195–1204.

67 Brightling CE, Ammit AJ, Kaur D, et al. TheCXCL10 ⁄ CXCR3 axis mediates human lung mast cell migra-tion to asthmatic airway smooth muscle. Am J Respir CritCare Med 2005; 171: 1103–1108.

68 Pennock JL & Grencis RK. The mast cell and gut nematodes:damage and defence. Chem Immunol Allergy 2006; 90: 128–140.

69 Ishizuka T, Okajima F, Ishiwara M, et al. Sensitized mastcells migrate toward the antigen: a response regulated by p38mitogen-activated protein kinase and Rho-associated coiled-coil-forming protein kinase. J Immunol 2001; 167: 2298–2304.

70 Jolly PS, Bektas M, Olivera A, et al. Transactivation of sphin-gosine-1-phosphate receptors by FcepsilonRI triggering isrequired for normal mast cell degranulation and chemotaxis.J Exp Med 2004; 199: 959–970.

71 Asai K, Kitaura J, Kawakami Y, et al. Regulation of mast cellsurvival by IgE. Immunity 2001; 14: 791–800.

72 Kalesnikoff J, Huber M, Lam V, et al. Monomeric IgE stimu-lates signaling pathways in mast cells that lead to cytokineproduction and cell survival. Immunity 2001; 14: 801–811.

73 Kawakami T & Galli SJ. Regulation of mast-cell and basophilfunction and survival by IgE. Nat Rev Immunol 2002; 2: 773–786.

74 Erb KJ. Helminths, allergic disorders and IgE-mediatedimmune responses: where do we stand? Eur J Immunol 2007;37: 1170–1173.

75 Mitre E, Norwood S & Nutman TB. Saturation of immuno-globulin E (IgE) binding sites by polyclonal IgE does notexplain the protective effect of helminth infections againstatopy. Infect Immun 2005; 73: 4106–4111.

76 Pochanke V, Koller S, Dayer R, et al. Identification and char-acterization of a novel antigen from the nematode Nippostron-gylus brasiliensis recognized by specific IgE. Eur J Immunol2007; 37: 1275–1284.

77 Carlos D, Sa-Nunes A, de Paula L, et al. Histamine modu-lates mast cell degranulation through an indirect mechanismin a model IgE-mediated reaction. Eur J Immunol 2006; 36:1494–1503.

78 Lin TJ & Befus AD. Differential regulation of mast cell func-tion by IL-10 and stem cell factor. J Immunol 1997; 159:4015–4023.

79 Yoshimoto T, Tsutsui H, Tominaga K, et al. IL-18, althoughantiallergic when administered with IL-12, stimulates IL-4and histamine release by basophils. Proc Natl Acad Sci USA1999; 96: 13962–13966.

80 Supajatura V, Ushio H, Nakao A, et al. Differential responsesof mast cell Toll-like receptors 2 and 4 in allergy and innateimmunity. J Clin Invest 2002; 109: 1351–1359.

81 Varadaradjalou S, Feger F, Thieblemont N, et al. Toll-likereceptor 2 (TLR2) and TLR4 differentially activate humanmast cells. Eur J Immunol 2003; 33: 899–906.

82 Qiao H, Andrade MV, Lisboa FA, Morgan K & Beaven MA.FcepsilonR1 and toll-like receptors mediate synergistic signalsto markedly augment production of inflammatory cytokinesin murine mast cells. Blood 2006; 107: 610–618.

83 Selvan RS, Butterfield JH & Krangel MS. Expression of mul-tiple chemokine genes by a human mast cell leukemia. J BiolChem 1994; 269: 13893–13898.

84 Shin K, Watts GF, Oettgen HC, et al. Mouse mast cell tryp-tase mMCP-6 is a critical link between adaptive and innateimmunity in the chronic phase of Trichinella spiralis infection.J Immunol 2008; 180: 4885–4891.

85 Huang C, Friend DS, Qiu WT, et al. Induction of a selectiveand persistent extravasation of neutrophils into the peritonealcavity by tryptase mouse mast cell protease 6. J Immunol1998; 160: 1910–1919.

86 Malaviya R, Ikeda T, Ross E & Abraham SN. Mast cell mod-ulation of neutrophil influx and bacterial clearance at sites ofinfection through TNF-alpha. Nature 1996; 381: 77–80.

87 Wong GW, Foster PS, Yasuda S, et al. Biochemical and func-tional characterization of human transmembrane tryptase(TMT) ⁄ tryptase gamma. TMT is an exocytosed mast cell pro-tease that induces airway hyperresponsiveness in vivo via aninterleukin-13 ⁄ interleukin-4 receptor alpha ⁄ signal transducerand activator of transcription (STAT) 6-dependent pathway.J Biol Chem 2002; 277: 41906–41915.

88 Sayed BA & Brown MA. Mast cells as modulators of T-cellresponses. Immunol Rev 2007; 217: 53–64.

89 Alizadeh H & Murrell KD. The intestinal mast cell responseto Trichinella spiralis infection in mast cell-deficient w ⁄ wvmice. J Parasitol 1984; 70: 767–773.

90 Ha TY, Reed ND & Crowle PK. Delayed expulsion of adultTrichinella spiralis by mast cell-deficient W ⁄ Wv mice. InfectImmun 1983; 41: 445–447.

91 Nawa Y, Kiyota M, Korenaga M & Kotani M. Defective pro-tective capacity of W ⁄ Wv mice against Strongyloides rattiinfection and its reconstitution with bone marrow cells. Para-site Immunol 1985; 7: 429–438.

92 Ben-Smith A, Lammas DA & Behnke JM. The relative invol-vement of Th1 and Th2 associated immune responses in theexpulsion of a primary infection of Heligmosomoides poly-gyrus in mice of differing response phenotype. J Helminthol2003; 77: 133–146.

93 Ford MJ, Bickle QD & Taylor MG. Immunity to Schistosomamansoni in congenitally athymic, irradiated and mast cell-depleted rats. Parasitology 1987; 94 (Pt 2): 313–326.

94 Meeusen EN, Balic A & Bowles V. Cells, cytokines and othermolecules associated with rejection of gastrointestinal nema-tode parasites. Vet Immunol Immunopathol 2005; 108: 121–125.

95 Betts CJ & Else KJ. Mast cells, eosinophils and antibody-mediated cellular cytotoxicity are not critical in resistance toTrichuris muris. Parasite Immunol 1999; 21: 45–52.

96 Uber CL, Roth RL & Levy DA. Expulsion of Nippostrongy-lus brasiliensis by mice deficient in mast cells. Nature 1980;287: 226–228.

97 Koyama K & Ito Y. Mucosal mast cell responses are notrequired for protection against infection with the murinenematode parasite Trichuris muris. Parasite Immunol 2000; 22:13–20.

98 Sher A, Correa-Oliveira R, Hieny S & Hussain R. Mechan-isms of protective immunity against Schistosoma mansoniinfection in mice vaccinated with irradiated cercariae. IV.Analysis of the role of IgE antibodies and mast cells. J Immu-nol 1983; 131: 1460–1465.

99 Rennick D, Hunte B, Holland G & Thompson-Snipes L.Cofactors are essential for stem cell factor-dependent growthand maturation of mast cell progenitors: comparative effectsof interleukin-3 (IL-3), IL-4, IL-10, and fibroblasts. Blood1995; 85: 57–65.



100 Barber KE, Crosier PS, Purdie KJ, et al. Human interleukin3: effects on normal and leukemic cells. Growth Factors 1989;1: 101–114.

101 Knight PA, Wright SH, Lawrence CE, Paterson YY & MillerHR. Delayed expulsion of the nematode Trichinella spiralis inmice lacking the mucosal mast cell-specific granule chymase,mouse mast cell protease-1. J Exp Med 2000; 192: 1849–1856.

102 Helmby H & Grencis RK. Contrasting roles for IL-10 in pro-tective immunity to different life cycle stages of intestinalnematode parasites. Eur J Immunol 2003; 33: 2382–2390.

103 Newlands GF, Miller HR, MacKellar A & Galli SJ. Stem cellfactor contributes to intestinal mucosal mast cell hyperplasiain rats infected with Nippostrongylus brasiliensis or Trichinellaspiralis, but anti-stem cell factor treatment decreases parasiteegg production during N. brasiliensis infection. Blood 1995;86: 1968–1976.

104 Lantz CS, Boesiger J, Song CH, et al. Role for interleukin-3in mast-cell and basophil development and in immunity toparasites. Nature 1998; 392: 90–93.

105 Dvorak AM, Seder RA, Paul WE, Morgan ES & Galli SJ.Effects of interleukin-3 with or without the c-kit ligand, stemcell factor, on the survival and cytoplasmic granule formationof mouse basophils and mast cells in vitro. Am J Pathol 1994;144: 160–170.

106 Sasaki Y, Yoshimoto T, Maruyama H, et al. IL-18 with IL-2protects against Strongyloides venezuelensis infection by acti-vating mucosal mast cell-dependent type 2 innate immunity.J Exp Med 2005; 202: 607–616.

107 Fallon PG, Jolin HE, Smith P, et al. IL-4 induces characteris-tic Th2 responses even in the combined absence of IL-5, IL-9,and IL-13. Immunity 2002; 17: 7–17.

108 Richard M, Grencis RK, Humphreys NE, Renauld JC & VanSnick J. Anti-IL-9 vaccination prevents worm expulsion andblood eosinophilia in Trichuris muris-infected mice. Proc NatlAcad Sci USA 2000; 97: 767–772.

109 Faulkner H, Renauld JC, Van Snick J & Grencis RK. Inter-leukin-9 enhances resistance to the intestinal nematode Tri-churis muris. Infect Immun 1998; 66: 3832–3840.

110 Fukao T, Yamada T, Tanabe M, et al. Selective loss of gastro-intestinal mast cells and impaired immunity in PI3K-deficientmice. Nat Immunol 2002; 3: 295–304.

111 Yanagida M, Fukamachi H, Ohgami K, et al. Effects of T-helper 2-type cytokines, interleukin-3 (IL-3), IL-4, IL-5, andIL-6 on the survival of cultured human mast cells. Blood1995; 86: 3705–3714.

112 Nilsson G, Miettinen U, Ishizaka T, Ashman LK, Irani AM& Schwartz LB. Interleukin-4 inhibits the expression of Kitand tryptase during stem cell factor-dependent developmentof human mast cells from fetal liver cells. Blood 1994; 84:1519–1527.

113 Lorentz A, Wilke M, Sellge G, et al. IL-4-induced priming ofhuman intestinal mast cells for enhanced survival and Th2cytokine generation is reversible and associated with increasedactivity of ERK1 ⁄ 2 and c-Fos. J Immunol 2005; 174: 6751–6756.

114 Mann-Chandler MN, Kashyap M, Wright HV, et al. IFN-gamma induces apoptosis in developing mast cells. J Immunol2005; 175: 3000–3005.

115 Yanagida M, Fukamachi H, Takei M, et al. Interferon-gamma promotes the survival and Fc epsilon RI-mediatedhistamine release in cultured human mast cells. Immunology1996; 89: 547–552.

116 Hu ZQ, Kobayashi K, Zenda N & Shimamura T. Tumornecrosis factor-alpha- and interleukin-6-triggered mast celldevelopment from mouse spleen cells. Blood 1997; 89: 526–533.

117 Matsuda H, Kannan Y, Ushio H, et al. Nerve growth factorinduces development of connective tissue-type mast cellsin vitro from murine bone marrow cells. J Exp Med 1991;174: 7–14.

118 Migliaccio AR, Rana RA, Sanchez M, et al. GATA-1 as a reg-ulator of mast cell differentiation revealed by the phenotype ofthe GATA-1low mouse mutant. J Exp Med 2003; 197: 281–296.

119 Tsai FY & Orkin SH. Transcription factor GATA-2 isrequired for proliferation ⁄ survival of early hematopoietic cellsand mast cell formation, but not for erythroid and myeloidterminal differentiation. Blood 1997; 89: 3636–3643.

120 Walsh JC, DeKoter RP, Lee HJ, et al. Cooperative and antag-onistic interplay between PU.1 and GATA-2 in the specifica-tion of myeloid cell fates. Immunity 2002; 17: 665–676.

121 Lawrence CE, Paterson YY, Wright SH, Knight PA & MillerHR. Mouse mast cell protease-1 is required for the enteropa-thy induced by gastrointestinal helminth infection in themouse. Gastroenterology 2004; 127: 155–165.

122 McDermott JR, Bartram RE, Knight PA, Miller HR, GarrodDR & Grencis RK. Mast cells disrupt epithelial barrier func-tion during enteric nematode infection. Proc Natl Acad SciUSA 2003; 100: 7761–7766.

123 Maruyama H, Yabu Y, Yoshida A, Nawa Y & Ohta N. A roleof mast cell glycosaminoglycans for the immunologicalexpulsion of intestinal nematode, Strongyloides venezuelensis.J Immunol 2000; 164: 3749–3754.

124 Amaral MM, Davio C, Ceballos A, et al. Histamine improvesantigen uptake and cross-presentation by dendritic cells.J Immunol 2007; 179: 3425–3433.

125 McIlroy A, Caron G, Blanchard S, et al. Histamine andprostaglandin E up-regulate the production of Th2-attractingchemokines (CCL17 and CCL22) and down-regulate IFN-gamma-induced CXCL10 production by immature humandendritic cells. Immunology 2006; 117: 507–516.

126 Jutel M, Watanabe T, Klunker S, et al. Histamine regulatesT-cell and antibody responses by differential expression of H1and H2 receptors. Nature 2001; 413: 420–425.

127 Tashiro M, Kawakami Y, Abe R, et al. Increased secretion ofTNF-alpha by costimulation of mast cells via CD28 and Fcepsilon RI. J Immunol 1997; 158: 2382–2389.

128 Frandji P, Oskeritzian C, Cacaraci F, et al. Antigen-dependentstimulation by bone marrow-derived mast cells of MHC classII-restricted T cell hybridoma. J Immunol 1993; 151: 6318–6328.

129 Fox CC, Jewell SD & Whitacre CC. Rat peritoneal mast cellspresent antigen to a PPD-specific T cell line. Cell Immunol1994; 158: 253–264.

130 Malaviya R, Twesten NJ, Ross EA, Abraham SN & PfeiferJD. Mast cells process bacterial Ags through a phagocyticroute for class I MHC presentation to T cells. J Immunol1996; 156: 1490–1496.

131 Melendez AJ, Harnett MM, Pushparaj PN, et al. Inhibitionof Fc epsilon RI-mediated mast cell responses by ES-62, aproduct of parasitic filarial nematodes. Nat Med 2007; 13:1375–1381.

132 Rhoads ML, Fetterer RH, Hill DE & Urban JF Jr. Trichurissuis: a secretory chymotrypsin ⁄ elastase inhibitor with poten-tial as an immunomodulator. Exp Parasitol 2000; 95: 36–44.



133 Stoten A, Huntley J, Mistry H, et al. Nonatopic allergen-independent mast cell activation in parasitized eosinophilicathymic rats. Parasite Immunol 2005; 27: 431–438.

134 Appelberg R. Neutrophils and intracellular pathogens:beyond phagocytosis and killing. Trends Microbiol 2007; 15:87–92.

135 Pham CT. Neutrophil serine proteases: specific regulators ofinflammation. Nat Rev Immunol 2006; 6: 541–550.

136 Tsuda Y, Takahashi H, Kobayashi M, Hanafusa T, HerndonDN & Suzuki F. Three different neutrophil subsets exhibitedin mice with different susceptibilities to infection by methicil-lin-resistant Staphylococcus aureus. Immunity 2004; 21: 215–226.

137 Ramalingam T, Rajan B, Lee J & Rajan TV. Kinetics of cellu-lar responses to intraperitoneal Brugia pahangi infections innormal and immunodeficient mice. Infect Immun 2003; 71:4361–4367.

138 Porthouse KH, Chirgwin SR, Coleman SU, Taylor HW &Klei TR. Inflammatory responses to migrating Brugia pahangithird-stage larvae. Infect Immun 2006; 74: 2366–2372.

139 Saeftel M, Volkmann L, Korten S, et al. Lack of interferon-gamma confers impaired neutrophil granulocyte function andimparts prolonged survival of adult filarial worms in murinefilariasis. Microbes Infect 2001; 3: 203–213.

140 Saeftel M, Arndt M, Specht S, Volkmann L & Hoerauf A.Synergism of gamma interferon and interleukin-5 in the con-trol of murine filariasis. Infect Immun 2003; 71: 6978–6985.

141 Brattig NW, Buttner DW & Hoerauf A. Neutrophil accumu-lation around Onchocerca worms and chemotaxis of neutro-phils are dependent on Wolbachia endobacteria. MicrobesInfect 2001; 3: 439–446.

142 Brigandi RA, Rotman HL, Yutanawiboonchai W, et al. Stron-gyloides stercoralis: role of antibody and complement inimmunity to the third stage of larvae in BALB ⁄ cByJ mice.Exp Parasitol 1996; 82: 279–289.

143 Herbert DR, Nolan TJ, Schad GA & Abraham D. The roleof B cells in immunity against larval Strongyloides stercoralisin mice. Parasite Immunol 2002; 24: 95–101.

144 Ligas JA, Kerepesi LA, Galioto AM, et al. Specificity andmechanism of immunoglobulin M (IgM)- and IgG-dependentprotective immunity to larval Strongyloides stercoralis in mice.Infect Immun 2003; 71: 6835–6843.

145 Watanabe K, Noda K, Hamano S, et al. The crucial roleof granulocytes in the early host defense against Strongy-loides ratti infection in mice. Parasitol Res 2000; 86: 188–193.

146 Padigel UM, Stein L, Redding K, et al. Signaling throughGalphai2 protein is required for recruitment of neutrophilsfor antibody-mediated elimination of larval Strongyloides ster-coralis in mice. J Leukoc Biol 2007; 81: 1120–1126.

147 Pesce JT, Liu Z, Hamed H, et al. Neutrophils clear bacteriaassociated with parasitic nematodes augmenting the develop-ment of an effective Th2-type response. J Immunol 2008; 180:464–474.

148 Tacchini-Cottier F, Zweifel C, Belkaid Y, et al. An immuno-modulatory function for neutrophils during the induction of aCD4+ Th2 response in BALB ⁄ c mice infected with Leishma-nia major. J Immunol 2000; 165: 2628–2636.

149 Beck-Schimmer B, Schwendener R, Pasch T, Reyes L, BooyC & Schimmer RC. Alveolar macrophages regulate neutrophilrecruitment in endotoxin-induced lung injury. Respir Res2005; 6: 61.

150 deSchoolmeester ML, Little MC, Rollins BJ & Else KJ.Absence of CC chemokine ligand 2 results in an alteredTh1 ⁄ Th2 cytokine balance and failure to expel Trichurismuris infection. J Immunol 2003; 170: 4693–4700.

151 Hirata M, Hara T, Kage M, Fukuma T & Sendo F. Neutro-penia augments experimentally induced Schistosoma japoni-cum egg granuloma formation in CBA mice, but not inC57BL ⁄ 6 mice. Parasite Immunol 2002; 24: 479–488.

152 Stadnyk AW, Dollard CD & Issekutz AC. Neutrophil migra-tion stimulates rat intestinal epithelial cell cytokine expressionduring helminth infection. J Leukoc Biol 2000; 68: 821–827.

153 Kaifi JT, Diaconu E & Pearlman E. Distinct roles forPECAM-1, ICAM-1, and VCAM-1 in recruitment of neutro-phils and eosinophils to the cornea in ocular onchocerciasis(river blindness). J Immunol 2001; 166: 6795–6801.

154 Gillette-Ferguson I, Daehnel K, Hise AG, et al. Toll-likereceptor 2 regulates CXC chemokine production and neutro-phil recruitment to the cornea in Onchocerca volvulus ⁄ Wolba-chia-induced keratitis. Infect Immun 2007; 75: 5908–5915.

155 Hall LR, Diaconu E, Patel R & Pearlman E. CXC chemokinereceptor 2 but not C-C chemokine receptor 1 expression isessential for neutrophil recruitment to the cornea in helminth-mediated keratitis (river blindness). J Immunol 2001; 166:4035–4041.

156 Bazzocchi C, Comazzi S, Santoni R, Bandi C, Genchi C &Mortarino M. Wolbachia surface protein (WSP) inhibitsapoptosis in human neutrophils. Parasite Immunol 2007; 29:73–79.

157 Falcone FH, Rossi AG, Sharkey R, Brown AP, Pritchard DI& Maizels RM. Ascaris suum-derived products induce humanneutrophil activation via a G protein-coupled receptor thatinteracts with the interleukin-8 receptor pathway. InfectImmun 2001; 69: 4007–4018.

158 Bower MA, Constant SL & Mendez S. Necator americanus:the Na-ASP-2 protein secreted by the infective larvae inducesneutrophil recruitment in vivo and in vitro. Exp Parasitol2008; 118: 569–575.

159 Ramirez BL, Howard OM, Dong HF, et al. Brugia malayiasparaginyl-transfer RNA synthetase induces chemotaxis ofhuman leukocytes and activates G-protein-coupled receptorsCXCR1 and CXCR2. J Infect Dis 2006; 193: 1164–1171.

160 Anbu KA & Joshi P. Identification of a 55 kDa Haemonchuscontortus excretory ⁄ secretory glycoprotein as a neutrophilinhibitory factor. Parasite Immunol 2008; 30: 23–30.

161 Moyle M, Foster DL, McGrath DE, et al. A hookworm gly-coprotein that inhibits neutrophil function is a ligand of theintegrin CD11b ⁄ CD18. J Biol Chem 1994; 269: 10008–10015.

162 Ali F, Brown A, Stanssens P, Timothy LM, Soule HR &Pritchard DI. Vaccination with neutrophil inhibitory factorreduces the fecundity of the hookworm Ancylostoma ceylani-cum. Parasite Immunol 2001; 23: 237–249.

163 Jefferies JR, Turner RJ & Barrett J. Effect of Fasciola hepa-tica excretory-secretory products on the metabolic burst ofsheep and human neutrophils. Int J Parasitol 1997; 27: 1025–1029.

164 Keir PA, Brown DM, Clouter-Baker A, Harcus YM &Proudfoot L. Inhibition of neutrophil recruitment by ES ofNippostrongylus brasiliensis. Parasite Immunol 2004; 26: 137–139.

165 Smith P, Fallon RE, Mangan NE, et al. Schistosoma mansonisecretes a chemokine binding protein with antiinflammatoryactivity. J Exp Med 2005; 202: 1319–1325.



166 Zang X, Atmadja AK, Gray P, et al. The serpin secreted byBrugia malayi microfilariae, Bm-SPN-2, elicits strong, butshort-lived, immune responses in mice and humans. J Immu-nol 2000; 165: 5161–5169.

167 Stanley P & Stein PE. BmSPN2, a serpin secreted by thefilarial nematode Brugia malayi, does not inhibit human neu-trophil proteinases but plays a noninhibitory role. Biochemis-try 2003; 42: 6241–6248.

168 Lantz CS, Yamaguchi M, Oettgen HC, et al. IgE regulatesmouse basophil Fc epsilon RI expression in vivo. J Immunol1997; 158: 2517–2521.

169 Seder RA, Plaut M, Barbieri S, Urban J Jr, Finkelman FD &Paul WE. Purified Fc epsilon R+ bone marrow and splenicnon-B, non-T cells are highly enriched in the capacity to pro-duce IL-4 in response to immobilized IgE, IgG2a, or ionomy-cin. J Immunol 1991; 147: 903–909.

170 Gibbs BF, Haas H, Falcone FH, et al. Purified human per-ipheral blood basophils release interleukin-13 and preformedinterleukin-4 following immunological activation. Eur JImmunol 1996; 26: 2493–2498.

171 Mitre E & Nutman TB. Basophils, basophilia and helminthinfections. Chem Immunol Allergy 2006; 90: 141–156.

172 Mitre E & Nutman TB. Lack of basophilia in human parasi-tic infections. Am J Trop Med Hyg 2003; 69: 87–91.

173 Falcone FH, Pritchard DI & Gibbs BF. Do basophils play arole in immunity against parasites? Trends Parasitol 2001; 17:126–129.

174 Hofstetter M, Fasano MB & Ottesen EA. Modulation of thehost response in human schistosomiasis. IV. Parasite antigeninduces release of histamine that inhibits lymphocyte respon-siveness in vitro. J Immunol 1983; 130: 1376–1380.

175 Gonzalez-Munoz M, Garate T, Puente S, Subirats M &Moneo I. Induction of histamine release in parasitized indivi-duals by somatic and cuticular antigens from Onchocerca vol-vulus. Am J Trop Med Hyg 1999; 60: 974–979.

176 Genta RM, Ottesen EA, Poindexter R, et al. Specific allergicsensitization to Strongyloides antigens in human strongyloi-diasis. Lab Invest 1983; 48: 633–638.

177 Nielsen BW. Basophil histamine release in allergic and non-allergic patient populations. Applications of a novel washedblood histamine release assay. Dan Med Bull 1995; 42: 455–472.

178 Mitre E, Taylor RT, Kubofcik J & Nutman TB. Parasite anti-gen-driven basophils are a major source of IL-4 in humanfilarial infections. J Immunol 2004; 172: 2439–2445.

179 King CL. Transmission intensity and human immuneresponses to lymphatic filariasis. Parasite Immunol 2001; 23:363–371.

180 Pritchard DI, Hooi DS, Brown A, Bockarie MJ, Caddick R& Quinnell RJ. Basophil competence during hookworm(Necator americanus) infection. Am J Trop Med Hyg 2007;77: 860–865.

181 Ogilvie BM, Askenase PW & Rose ME. Basophils and eosi-nophils in three strains of rats and in athymic (nude) rats fol-lowing infection with the nematodes Nippostrongylusbrasiliensis or Trichinella spiralis. Immunology 1980; 39: 385–389.

182 Okada M, Nawa Y, Horii Y, Kitamura T & Arizono N.Development of basophils in Mongolian gerbils: formation ofbasophilic cell clusters in the bone marrow after Nippostron-gylus brasiliensis infection. Lab Invest 1997; 76: 89–97.

183 Mitchell EB & Askenase PW. Basophils in human disease.Clin Rev Allergy 1983; 1: 427–448.

184 Sokol CL, Barton GM, Farr AG & Medzhitov R. A mechan-ism for the initiation of allergen-induced T helper type 2responses. Nat Immunol 2008; 9: 310–318.

185 Reese TA, Liang HE, Tager AM, et al. Chitin induces accu-mulation in tissue of innate immune cells associated withallergy. Nature 2007; 447: 92–96.

186 Aumuller E, Schramm G, Gronow A, et al. Echinococcus mul-tilocularis metacestode extract triggers human basophils torelease interleukin-4. Parasite Immunol 2004; 26: 387–395.

187 Phillips C, Coward WR, Pritchard DI & Hewitt CR. Baso-phils express a type 2 cytokine profile on exposure to pro-teases from helminths and house dust mites. J Leukoc Biol2003; 73: 165–171.

188 Schramm G, Mohrs K, Wodrich M, et al. Cutting edge:IPSE ⁄ alpha-1, a glycoprotein from Schistosoma mansonieggs, induces IgE-dependent, antigen-independent IL-4 pro-duction by murine basophils in vivo. J Immunol 2007; 178:6023–6027.

189 Gnanasekar M, Rao KV, Chen L, et al. Molecular characteri-zation of a calcium binding translationally controlled tumorprotein homologue from the filarial parasites Brugia malayiand Wuchereria bancrofti. Mol Biochem Parasitol 2002; 121:107–118.

190 Hartmann S, Sollwedel A, Hoffmann A, Sonnenburg B &Lucius R. Characterization of IgE responses in a rodentmodel of filariasis and the allergenic potential of filarial anti-gens using an in vitro assay. Parasite Immunol 2003; 25: 9–16.

191 Hida S, Yamasaki S, Sakamoto Y, et al. Fc receptor gamma-chain, a constitutive component of the IL-3 receptor, isrequired for IL-3-induced IL-4 production in basophils. NatImmunol 2009; 10: 214–222.

192 Yoshimoto T & Nakanishi K. Roles of IL-18 in basophilsand mast cells. Allergol Int 2006; 55: 105–113.

193 Min B, Prout M, Hu-Li J, et al. Basophils produce IL-4 andaccumulate in tissues after infection with a Th2-inducingparasite. J Exp Med 2004; 200: 507–517.

194 Ohnmacht C & Voehringer D. Basophil effector function andhomeostasis during helminth infection. Blood 2009; 113:2816–2825.

195 Khodoun MV, Orekhova T, Potter C, Morris S & FinkelmanFD. Basophils initiate IL-4 production during a memory T-dependent response. J Exp Med 2004; 200: 857–870.

196 Denzel A, Maus UA, Rodriguez Gomez M, et al. Basophilsenhance immunological memory responses. Nat Immunol2008; 9: 733–742.

197 Tsujimura Y, Obata K, Mukai K, et al. Basophils play a pivo-tal role in immunoglobulin-G-mediated but not immunoglo-bulin-E-mediated systemic anaphylaxis. Immunity 2008; 28:581–589.

198 Mack M, Schneider MA, Moll C, et al. Identification of anti-gen-capturing cells as basophils. J Immunol 2005; 174: 735–741.

199 Hida S, Tadachi M, Saito T & Taki S. Negative control ofbasophil expansion by IRF-2 critical for the regulation ofTh1 ⁄ Th2 balance. Blood 2005; 106: 2011–2017.

200 Oh K, Shen T, Le Gros G & Min B. Induction of Th2 typeimmunity in a mouse system reveals a novel immunoregula-tory role of basophils. Blood 2007; 109: 2921–2927.



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