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capable of handling up to 120 tests per hourand automatically controls all aspects ofsystem management. There are more than75 immunoassays available in this range.Reader Enquiry No. 102

rProtein LFrom Actigen

Three conjugated forms of this recentlyintroduced affinity binding protein

rProtein L is now supplied conjugated withhorseradish peroxidase (HRP), alkalinephosphatase (AP) or biotin, as well as beingavailable in the unconjugated form. All areavailable in 1-mg quantities in solution.Applications for rProtein L include thepurification and detection of immunoglobu-lins containing k light chains, purification ofFab and scFv fragments and the purificationof monoclonal antibodies directly frommedia supplemented with BSA or FCS.Coupling rProteinL to HRP and AP enableseasy detection in western blotting and ELISAsystems, for example, whereas biotin-conju-gated rProtein L has applications in the mag-netic separation and detection of antibodies.This is a recombinant protein derived fromthe bacterium Peptostreptococcus magnus. Itbinds immunoglobulins primarily through klight chain interactions without interferingwith antigen binding.Reader Enquiry No. 103

Mega Cult-C From Stem Cell

A new collagen-based kit for identifying andquantifying megakaryocytic progenitors

This procedure is stated to take less than twoweeks from start to finish and is based on cul-ture fixation and staining performed directlyon a standard-size slide. A serum-free growthmedium is used to assay for human mega-

karyocytic progenitor cells, as fetal bovineserum contains inhibitors to growth. Theidentification, cloning and availability ofrecombinant cytokines, notably thrombopoi-etin, has permitted the optimization of con-ditions for the proliferation and differentia-tion of CFU-Mk (colony forming unit-megakaryocyte). Furthermore, the use of acompatible gelling agent allowing clonalprogeny of a single cell to stay together isessential for colony formation. In this system,collagen acts as a stable gel matrix to supportgrowth and development, and allows in situimmunocytochemical staining of colonieswithin the dehydrated gel. The staining sys-tem identifies three colony types: pure Mk,mixed Mk/non-Mk and non-Mk. A perma-nent record of assay results can be stored instandard slide boxes.Reader Enquiry No. 104

ActiCyte-TCFrom BioErgonomics

A complete turnkey system for isolation andactivation of human peripheral blood T cells

Each ActiCyte-TC kit includes PrepaCyte-SCmedium for rapid isolation of T cells,VitaLyse for removal of residual contaminat-ing erythrocytes, a medium for T-cell activa-tion via cell-surface receptors and a T-cellbasal medium for non-activated cultures.Part of a complete T-cell activation system,the kits should be useful for studying recep-tor expression and cytokine production andsecretion. Reader Enquiry No. 105

b2m/Abb double knockout mice

From Taconic

Mice that lack expression of both classes ofMHC antigens

This animal model may be useful for exam-ining compensation mechanisms in severelyimmunocompromised animals. These micecombine the characteristics of two individ-ual ‘knockouts’: the b2m and the Ab

b (rele-vant to transplantation, gene therapy andinfectious disease studies). Moreover, theb2m/Ab

b double knockout mouse has lowlevels of MHC (major histocompatibilitycomplex) class I heavy-chain expression, nodetectable MHC class II expression andreduced levels of both CD4& and CD8& Tcells. These mice were developed by homol-ogous recombination, are available on aninbred C57BL/6 background and carry anH2b haplotype. They were bred by matingthe MHC class I-deficient b2m knockoutmodel with the MHC class II-deficient Ab

b

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NATURE | VOL 392 | 5 MARCH 1998 107

Antigen retrieval kitFrom BioGenex

This antigen retrieval technique restoresimmunoreactivity of antigens in formalin-fixed tissue sections

The technique consists of heating the tissuesections in a microwave oven in the presenceof retrieval solutions. This accessory kit con-sists of slide holders and slide baths, and toaccommodate microwave heating, the bathsand holders are made of heat-stable thermo-plastic resins, which may be used with orwithout a pressure cooker. Three antigenretrieval solutions covering a wide pH rangeare available for use with the accessory kit,namely Citra, AR-IO and Glyca.Reader Enquiry No. 100

Architect i 2000From Abbott Laboratories

Flexible instrumentation that helps to meetimmunoassay and chemistry testing needs

As a monomeric unit, the i2000 is said to becapable of performing up to 200 tests perhour and processing up to 1,600 tests pereight-hour shift. It provides continuous,random sample access and accommodates125- or 250-primary-tube loadup for maxi-mum walk-away capability. The i2000 canbe upgraded by combining up to four i2000modules through one operator, thus creat-ing an i8000. The i8000 is stated to performup to 800 tests per hour with an onboardreagent capacity of 100 different refrigeratedimmunoassays and 50,000 tests. The i2000launch provides 26 assays and featuresChemiflex technology, which incorporateschemiluminescent technology and flexibleprotocols. The Architect family comprisesthree product lines, including the i series(immunoassay), the c series (chemistry) andthe ci series (chemistry and immunoassay).Reader Enquiry No. 101

Immunology

Immulite IL-8 assay From DPC

A fully automated, random-accessinterleukin-8 (IL-8) assay

Designed for research into inflammatoryreactions, regulatory functions, pathologi-cal conditions and disease states, this assayhas a working range of 20–10,000 pg ml11,with a sensitivity of 6.2 pg ml11, and run-times of about 40 minutes. The assay hasbeen calibrated against NIBSC 89/520 andis specific for IL-8, showing no cross reac-tivity with other chemokines. The system is

Antibodies and immunologyThis group of products includes a collagen-based kit for identifying and quantifying megakaryocytic progenitors,flow cytometry reagents, an antigen retrieval kit and a permeabilization reagent to help detect intracellular antigens.

DPC’s Immulite assays help study disease states.

Nature © Macmillan Publishers Ltd 1998

8knockout mouse, which are depleted ofCD8& and CD4& T cells, respectively. The B-cell compartment of these animals appearsintact, and MHC-deficient mice can mountspecific antibody responses when challengedwith a T cell-independent antigen.Reader Enquiry No. 106

Spin cycle

RC12BP centrifugeFrom Sorvall

A blood-processing centrifuge system forincreased productivity and GMP compliance

Capable of accommodating twelve 500-mlblood bags at a time, this centrifuge isdesigned for low-speed centrifugation andimproved GMP compliance in blood com-ponent manufacture. With a top speed of4,700 r.p.m. (7,333g), this machine uses anaccumulated centrifugal effect to ensurereproducible, consistent separations regard-less of rotor load differences, and a slowstart/stop system, which controls rates ofacceleration and deceleration to reduce sam-ple resuspension. There are ten differentacceleration and deceleration profiles, thatcan be customized for minimal sampleresuspension, cleaner interfaces and higherproduct yields. The software improves GMPcompliance by allowing up to 16 centrifugesfrom this series to be networked to a singlePC for centralized data recording andprocess control. Also aiding efficiency is abarcode scanner that matches process datato identification numbers for componenttraceability. Reader Enquiry No. 107

Assays and cytometry

Flow cytometry reagentsFrom Stratech Scientific

A collection of single- and multi-colourproducts, controls and intracellular cytokines

These products are designed and titred towork with all the major flow cytometryinstruments. All five-, four-, three- and two-colour products have been optimized for usewith single- or dual-laser configurations.According to the manufacturer, users accus-tomed to looking at one or two populationscould be analysing 16 or more at a time in asingle tube. Kits for staining intracellularantigens are also offered. Each kit containspre-mixed solutions for fixation, permeabi-lization and washing, plus an easy-to-useand optimized protocol.Reader Enquiry No. 108

AC133-cell antigenFrom Miltenyi Biotec

A monoclonal antibody to a novel glycoproteinantigen

Selectively expressed on the surface of imma-ture haematopoietic progenitor cells, thisantigen is not detectable on other blood cells,endothelial cells, fibroblasts or myeloidleukaemia cells. AC133-selected cells includethe haematopoietic long-term re-populationcells demonstrated in a fetal sheep transplan-tation model. This mAb provides an alterna-tive to CD34 for the selection and characteri-zation of cells necessary for transplantsituations, for studies of ex vivo expansionstrategies and gene therapy studies. AC133has been conjugated to the company’s MACSMicroBeads for magnetic cell sorting, as wellas phycoerythrin for flow cytometric analysis.Reader Enquiry No. 109

Inno-LIA ANAFrom Microgen Bioproducts

A multi-parametric immunoassay to detectand differentiate antinuclear antibodies inserum for autoimmune disease diagnosis

Using a new approach to antinuclear anti-body (ANA) testing, this assay system uti-lizes mainly recombinant antigens, allowingit to provide simultaneously information onantibodies to 10 autoantigens and 14 deter-minants within three hours. Trials indicatedthat there is increased sensitivity for thedetection of anti-Ro52 and anti-La, more sothan with a combination of conventionaltechniques, and it maintains high diseasespecificity, says Microgen. New diagnosticinsights gleened from this assay include thepreviously undetected high frequency ofanti-Ro52 antibodies found in polymyositis.Efficient high-throughput testing can beachieved using the optional Auto-LIA auto-mated instrument, and objective reading,quantitation and data management is pro-vided with optional LIA-Scan software.Reader Enquiry No. 110

BDNF Emax

From Promega

The brain-derived neurotrophic factor(BDNF) immunoassay system now comes inan optimized antibody sandwich format

After an overnight coating of a 96-well platewith anti-BDNF mAb, the specific protein iscaptured and detected using a BDNF poly-clonal antibody (pAb) and a species-specific,anti-IgY antibody conjugated to horseradishperoxidase (HRP). Incubation with a chro-mogenic substrate causes a colour change,easily measured by a plate reader, that is pro-portional to the amount of BDNF present.The system can be used to quantify BDNF intissue culture supernatants, plasma, serum,urine or tissue extracts. It is recommended

for use in human, mouse, rat, rhesus mon-key, goat, sheep, pig and horse studies. Ittypically has less than 3% cross-reactivitywith other related neurotrophic factors(NGF, NT-3 and NT-4) at 100 ng ml11. Theassay has a stated minimum sensitivity of15.6 pg ml11 of BDNF.Reader Enquiry No. 111

IntraPrepFrom Coulter

A new permeabilization reagent forintracellular antigen detection

Formulated for the exploration of intra-cellular antigen expression by flow cytom-etry, this reagent allows access to bothcytoplasmic and nuclear antigens whilepreserving light-scatter characteristics andsurface-antigen expression. The completekit offers ready-to-use reagents, formulatedto reduce nonspecific staining, and a fast,simple procedure for sample preparation. Reader Enquiry No. 112

On the webCambridge Research Biochemicals offers itsantibody guide. The guide can be found at<www.ZenecaLSM.co.uk/crb>.These notes are compiled by Brendan Hortonfrom information provided by the manufacturers.For more details, fill in the reader service cardbound inside the journal.

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A double knockout — Taconic’s compromisedmouse lacks both MHC antigens.

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