FAILURE OF HUMAN DEFENSE MECHANISMS

FAILURE OF HUMAN DEFENSE MECHANISMS

FAILURE OF HUMAN DEFENSE MECHANISMS

* Mechanisms of Failure* Evasion and subversion of the immune system by

pathogens* Immunodeficiencies

* Inherited (Primary)

* Acquired (Secondary)* Malnutrition* Drugs* Radiation* Pathogens

MECHANISMS OF EVASION AND SUBVERSION BY PATHOGENS

* Genetic variation (antigenic differences)* Numerous different surface antigens (serotypes /

serovars) without modification* Streptococcus pneumoniae

* 90 serotypes (capsular polysaccharides)

* Salmonella species

* 2,500 serotypes (cell wall polysaccharides)

* Rhinoviruses

* 100 serotypes (capsid proteins)

* Poliovirus

* 3 serotypes (capsid proteins)

MECHANISMS OF EVASION AND SUBVERSION BY PATHOGENS

* Genetic variation (antigenic differences)* Few different surface antigens with frequent modification

* Influenza viruses * Classification into “types” on nucleoprotein

* A, B and C

* Classification of Influenza A virus into “subtypes* Hemagglutinin (HA or H)

* Avian (16) and Human (3)

* Neuramindase (NA or N)

* Avian (9) and Human (2)

* Influenza A subtypes (H3N2, H1N1, H5N1)

MECHANISMS OF GENETIC CHANGE IN INFLUENZA A VIRUS

* Antigenic Drift* Point mutations in HA and NA genes

* No proofreading of replication

* Minor antigenic change resulting in new “strains”

* Antigenic Shift* Re-assortment of gene segments from avian and human viruses in

same host (swine or humans)

* Major antigenic change resulting in new “subtype” of Influenza A virus

MECHANISMS OF EVASION AND SUBVERSION BY PATHOGENS

* Establishment of a dormant state (latency) with reactivation

* Blocking of antigen processing and presentation* MHC I degradation

* Interference with proteasome

* Interference with TAP

* Interference with Tapasin

* Retention of MHC 1 in ER

* Interference with NKG2A receptor

* Inhibition of humoral immunity

MECHANISMS OF EVASION AND SUBVERSION BY PATHOGENS

* Characteristic of the Herpesviruses* Herpes simplex virus, type 1 (HSV-1)

* Herpes simplex virus, type 2 (HSV-2)

* Varicella-Zoster virus (VZV)

* Epstein-Barr virus (EBV)

* Cytomegalovirus (CMV)

* Human herpesvirus 6 (HHV-6)

* Human herpesvirus 7 (HHV-7)

* Human herpesvirus 8 (HHV-8)

HUMAN HERPES VIRUS 8 (HHV-8)

* One of seven oncogenic virusesOne of seven oncogenic viruses

* History of stealing human genesHistory of stealing human genes* IL-6, BCL-2, cyclin DIL-6, BCL-2, cyclin D

* Etiologic agentEtiologic agent* Kaposi’s sarcomaKaposi’s sarcoma* Multicentric Castleman’s DiseaseMulticentric Castleman’s Disease

* Non-malignant tumor in lymph nodesNon-malignant tumor in lymph nodes* Hyperproliferation of B cellsHyperproliferation of B cells

HUMAN HERPES VIRUS 8 (HHV-8)

* Target cell for latencyTarget cell for latency* B lymphocyteB lymphocyte

* Mechanism of latency (genes and proteins)Mechanism of latency (genes and proteins)* Cyclin DCyclin D* LANA (latency associated nuclear antigen)LANA (latency associated nuclear antigen)* K 13K 13

* Blocks Fas apotosis pathwayBlocks Fas apotosis pathway

* Target cell for Kaposi’s sarcomaTarget cell for Kaposi’s sarcoma* Spindle cellSpindle cell

MECHANISMS OF SUBVERSION OF THE IMMUNE SYSTEM

* Production of exotoxins (superantigens)* Staphylococcus aureus* Streptococcus pyogenes

* Staphylococcus aureus superantigens* Toxic shock syndrome toxin-1 (TSST-1)

* 75% of cases (99% M and 40% NM)

* Staphylococcal enterotoxin B (SEB)* 20% of cases

* Staphylococcal enterotoxin C (SEC)

MECHANISMS OF SUBVERSION OF THE IMMUNE SYSTEM

* Streptococcus pyogenes superantigens* Streptococcus pyrogenic exotoxins A, B and C

* Exotoxins produced primarily from M types* 1 and 3

* Mechanism of action* Activation of 5 to 30% of T cells* Cytokine storm

TOXIC SHOCK SYNDROME (TSS)

* Staphylococcal TSS* First reported in 1978 followed by outbreak in 1980

* Clinical manifestations (acute onset)* Fever (>102 F), chills, headache* Hypotension (<90 mmHg)* Diffuse macular erythroderma rash* Myalgias* Nausea, vomiting and diarrhea * Cutaneous desquamation (palms and soles)

IMMUNODEFICIENCY DISEASES

* A group of diseases where one or more components of the immune system are either absent or defective

* Classification* Primary (Inherited)

* Gene defects may be autosomal or X-linked

* Secondary (Acquired)* Malnutrition, diseases, drugs, radiation, microorganisms

COMPONENTS OF THE IMMUNE SYSTEM AND CLINICAL PRESENTATION IN IMMUNODEFICIENCY DISEASES

* Humoral* Persons with history of recurrent infections with

encapsulated bacteria* Streptococcus pneumoniae

* Haemophilus influenzae

* Cellular (Cell mediated)* Persons with history of recurrent infections with

opportunistic pathogens* Pneumocystis jiroveci (carinii)

EVALUATION OF PATIENTS WITH IMMUNODEFICIENCY DISEASES

* Humoral* Measure antibody levels by nephelometry

* IgM* IgG + subclasses* IgA + subclasses

* Measure absolute number and percent of B cells by flow cytometry

* Cellular* Measure absolute numbers and percentages of T

lymphocytes by flow cytometry

PRIMARY IMMUNODEFICIENCY DISEASES

* WHO currently recognizes 100 primary immunodeficiency diseases* < 20 account for >90% of all cases

* General Classification* Primarily humoral deficiency* Primarily cellular deficiency * Combined humoral and cellular deficiency* Phagocyte dysfunction or deficiency* Complement deficiency* MHC deficiency

PRIMARY IMMUNODEFICIENCY DISEASES

* Prevalence of primary immunodeficiency diseases

* B cell (50 to 60%)* T cell (5 to 10%)* B and T cells (20%)* Phagocytes (10 to 15%)* Complement (2%)* NK (< 0.1%)

PRIMARY IMMUNODEFICIENCY DISEASES

* Most common primary immunodeficiency diseases

* B cell Selective IgA deficiency* T cell DiGeorge syndrome ZAP-70 deficiency* B and T cells SCID* Phagocytes Chronic granulomatous disease* Complement Immune complex disease* NK Viral infections and tumors

PRIMARY IMMUNODEFICIENCY DISEASES

* Gene defects * Autosomal recessive or dominant* X-linked

* Examples* CVID (autosomal dominant)* Selective IgA (autosomal dominant)* Hyper-IgM (autosomal recessive or X-linked)* Classic complement (autosomal recessive)

* First PID described in 1952* Bruton’s X-linked agammaglobulinemia

CASE STUDY – 13 YEAR OLD MALE

* Bone marrow transplantation (BMT) for SCIDBone marrow transplantation (BMT) for SCID* BM from sister was unmatchedBM from sister was unmatched

* 3 months later developed3 months later developed* FeverFever* Nausea, vomiting and diarrheaNausea, vomiting and diarrhea* Abdominal painAbdominal pain* Intestinal bleedingIntestinal bleeding

* Autopsy revealedAutopsy revealed* Hundreds of intraabdominal malignant tumorsHundreds of intraabdominal malignant tumors

CASE STUDY – DAVID P. VETTER

* Parents – David J and Carol AnnParents – David J and Carol Ann

* ChildrenChildren* Katherine (1968)Katherine (1968)* David J III (1970)David J III (1970)

* Died of SCID at 7 monthsDied of SCID at 7 months

* Advised of risk of another male childAdvised of risk of another male child

* David P born on September 21, 1971David P born on September 21, 1971* Unmatched BMT on 12/21/83Unmatched BMT on 12/21/83* Died of SCID on 2/22/84Died of SCID on 2/22/84

SELECTIVE IgA DEFICIENCY

* Most common and mildest of PI

* Prevalence* 1 in 700 caucasians* 1 in 18,000 Japanese

* Majority of patients are asymptomatic

* Clinical presentation* Recurrent sinopulmonary and GI disease, allergy, autoimmunity

SELECTIVE IgA DEFICIENCY

* Incidence of allergy and asthma is increased* Food allergy* Asthma may be more severe* Allergic rhinitis

* Incidence of autoimmune disease is increased* Rheumatoid arthritis (RA)* Systemic lupus erythematosus (SLE)

* Mechanism is unclear* 30% of patients have Anti-IgA (IgG > IgM > IgE)

SELECTIVE IgA DEFICIENCY

* IgA deficiency significant risk factor for* Anaphylactic transfusion reactions

* Mechanism is unclear* Classic anaphylaxis involves IgE

* Anti-IgA, IgG most prevalent

* Definition* Deficiency (< 7 mg/dL)

* Severe deficiency (<0.05 mg/dL)

SELECTIVE IgG DEFICIENCY

* Selective IgG subclass deficiency * IgG2 in children* IgG3 in adults

* Combined deficiency relatively common* IgG2 with IgA* IgG1 and IgG3* IgG2 and IgG4

* Clinical presentation* Recurrent upper and lower respiratory tract infections

SELECTIVE IgG DEFICIENCY – CASE STUDY

* 9 year old male presented to family physician by his mother for evaluation of short stature and recurrent infections

* Past medical history* Recurrent URI and LRI with

* Streptococcus pneumoniae, Haemophilus influenzae, Influenza virus, Respiratory Syncytial Virus, Parainfluenza virus

* 2 to 3 each year since age 1

* Recurrent diarrhea since age 4

SELECTIVE IgG DEFICIENCY – CASE STUDY

* Laboratory results for total serum antibodies* IgG of 6.0 gm/L (5.4 to 16.1 gm/L)* IgA of 0.9 gm/L (0.7 to 2.5 gm/L)* IgM of 0.6 gm/L (0.5 to 1.8 gm/L)

* Laboratory results for IgG subclasses* IgG1 of 4.6 gm/L (3.6 to 7.3 gm/L)* IgG2 of 0.1 gm/L (1.4 to 4.5 gm/L)* IgG3 of 0.5 gm/L (0.3 to 1.1 gm/L)* IgG4 of 0.2 gm/L (0.1 to 1.0 gm/L)

CORRECTION OF GENETIC DEFECTS OF IMMUNE SYSTEM

* Many immunodeficiencies affect hematopoietic cells

* Correction of deficiency by transplantation of * Bone marrow (hematopoietic stem cells)

* Success depends on degree of HLA matching between donor and recipient

* Major complication graft-versus-host disease (GVHD)

* Somatic gene therapy* Functional copy of defective gene inserted into patients stem

cells

SECONDARY (ACQUIRED) IMMUNODEFICIENCY DISEASES

* Malnutrition

* Diseases* Diabetes, nephrotic syndrome, protein-losing enteropathy

* Drugs* Corticosteroids

* Hydrocortisone, methylprednisolone, prednisone

* Immunosuppressants* Azathioprine, tacrolimus, cyclosporine A

ACQUIRED IMMUNODEFICIENCY DISEASES

* Radiation

* Microorganisms* Human T-cell lymphotropic virus, type I (HTLV-I)* Mycobacterium leprae

* Lepromatous leprosy

* Cytomegalovirus (CMV)* Epstein-Barr virus (EBV)* Human immunodeficiency virus (HIV)

CASE STUDY –20 YEAR OLD MALE

* Presented to ER of Southeast Regional Medical Center in Lumberton, NC* Headache, fever, chills, AMS and nuchal rigidity

* Blood cultures collected, but lumbar puncture was unsuccessful

* Treated with single 2 gram dose of ceftriaxone

* Transferred to New Hanover Regional Medical Center in Wilmington, NC

CASE STUDY (20 M) –PHYSICAL EXAMINATION

* VITAL SIGNS* Temperature 100 F, PR 92, RR 20, BP 120/60

* HEENT AND NECK* Pupils equal, round and light reactive* Nuchal rigidity is positive

* LYMPH NODES* No lymphadenopathy

* ABDOMEN* Soft. No distention, tenderness, organomegaly

* EXTREMITIES* Bilateral upper and lower clubbing

* NEUROLOGIC* Babinski is negative and Kernig is positive

CASE STUDY –20 YEAR OLD MALE

* Past medical history* Recurrent infections (age 10)

* Sinusitis* Pneumococcal pneumonia and bacteremia

* Specimens collected for culture at NHRMC* Blood, CSF and ear drainage

* Treatment at NHRMC* Ceftriaxone (2 grams IV q12) and vancomycin (1 gram IV

q12)

CASE STUDY (20 M) – COMPREHENSIVE METABOLIC PANEL (CMP)

Patient Reference* Glucose 172 72 - 112 mg/dL* BUN 7 7 - 18 mg/dL* Creatinine 0.7 0.5 - 1.2 mg/dL* Sodium 139 136 - 146 mmol/L* Potassium 3.8 3.7 - 5.2 mmol/L* Chloride 106 98 - 108 mmol/L* Calcium 8.3 8.5 - 10.5 mg/dL* Total Protein 4.8 6.1 - 8.0 mg/dL* Albumin 2.6 3.5 - 4.8 g/dL* Bilirubin (T) 0.6 0.0 - 1.0 mg/dL* AST 7 15 - 37 U/L* ALT 22 19 - 55 U/L* Alk Phos 63 50 - 136 U/L

CASE STUDY (20 M) –CBC WITH DIFF

Patient Reference* WBC 19.8 4.8 - 10.8 K/uL* RBC 4.2 4.9 - 6.1 M/uL* Platelets 278 145 - 400 K/uL* HGB 11.5 14.0 - 18.0 g/dL* HCT 33.6 40 - 52 %* Neutrophils 85 40 - 74 %* Lymphocytes 7 15 - 47 %* Monocytes 7 0 - 12 %* Eosinophils 0 0 - 6 %* Basophils 0 0 - 2 %

CASE STUDY (20 M) –URINE DRUG SCREEN

* PCP Negative* Benzodiazepine Negative* Cocaine Negative* Amphetamine Negative* THC Negative* Opiates Negative* Barbiturates Negative* Methadone Negative* Tricyclic Antidepressants Negative

CASE STUDY (20 M) – COAGGULATION/HEMATOLOGY

Patient Reference* PT 16.6 10.7 - 13.5 seconds* INR 1.93 0.86 - 1.34 seconds* PTT 42.8 25 - 38 seconds

* Fibrinogen 711 160 - 440 mg/dL* Haptoglobin 425 43 - 212 mg/dL* Sed rate 60 0 - 15 mm/hr

CASE STUDY (20 M) – CEREBROSPINAL FLUID

* Glucose 0 40 - 70 mg/dL* Protein 314 15 - 45 mg/dL* Lactic acid 17.6 < 2.8 mmol/L* WBC 568 uL* RBC 373 uL* Neutrophils 73 %* Lymphocytes 11 %* Monocytes 16 %* VDRL Negative Negative

CASE STUDY (20 M) – MICROBIAL ANTIGENS (CSF)

* Haemophulus influenzae, type B Negative* Streptococcus pneumoniae Negative* Streptococcus agalactiae (GBS) Negative* Neisseria meningitidis (C, W135) Negative* Neisseria meningitidis (A, Y) Negative* Neisseria meningitidis (B)/ E.coli Negative

* Cryptococcus neoformans Negative

CASE STUDY (20 M) –CULTURE AND SMEAR (CSF)

* Routine* 2 to 6 WBC/HPF* No organisms seen on gram stained smear

* Acid-fast bacilli* No acid fast bacilli (AFB) seen on fluorochrome stained

smear

* Fungus* No fungal elements seen on PAS stained smear

CASE STUDY (20 M) –CBC WITH DIFF (DAY 2)

Patient Reference* WBC 14.5 4.8 - 10.8 K/uL* RBC 3.73 4.6 - 6.1 M/uL* Platelets 302 145 - 400 K/uL* HGB 10.0 14.0 - 18.0 g/dL* HCT 30.0 40.0 - 52.0 %* Neutrophils 76 40 - 74 %* Lymphocytes 16 15 - 47 %* Monocytes 8 0 - 12 %* Eosinophils 0 0 - 6 %* Basophils 0 0 - 2 %

CASE STUDY (20 M) –CMP (DAY 2)

Patient Reference

* Glucose 129 72 - 112 mg/dL

* Protein(T) 5.2 6.1 - 8.0 g/dL

* Albumin 2.3 3.5 - 4.8 g/dL

* AST 2.0 15 - 37 U/L

All other analytes within reference ranges

CASE STUDY (20 M) –CSF STUDIES (DAY 3)

Patient Reference* Glucose 34 40 - 70 mg/dL* Protein 100 15 - 45 mg/dL* WBC 576 uL* RBC 14 uL* Neutrophils 42 %* Lymphocytes 28 %* Monocytes 30 %

* Bacterial antigens Negative Negative

CASE STUDY (20 M) – CSF CULTURE AND SMEAR (DAY 3)

* Routine* 0 to 1 WBC/HPF* No organisms seen on gram stained smear

* Acid-fast bacilli* No acid fast bacilli seen on fluorochrome stained smear

* Fungus* No fungal elements seen on PAS stained smear

CASE STUDY (20 M) – MOLECULAR MICROBIOLOGY (DAY 3)

* Cerebrospinal fluid (CSF) by PCR

* HSV-1 and HSV-2 DNA Negative

* Enterovirus RNA Negative

* Borrelia burgdorferi DNA Negative

CASE STUDY (20 M) – MICROBIOLOGY AT NHRMC (DAY 3)

* Ear drainage growth* Pseudomonas aeruginosa

* Blood cultures * Negative at day 3 and day 5

* Cerebrospinal fluid cultures* Negative

CASE STUDY (20 M) –BLOOD CULTURES (SRMC-DAY 3)

* Streptococcus pneumoniae

* Penicillin G Resistant* Ceftriaxone Resistant* Azithromycin Resistant* Trim/Sulfa Resistant* Chloramphenicol Susceptible* Moxifloxacin Susceptible* Tetracycline Susceptible* Vancomycin Susceptible

CASE STUDY (20 M) - IMMUNOLOGY (DAY 3)

* Consultation between infectious disease and clinical microbiology* Monospot test

* RPR

* Antinuclear antibody (ANA)

* Complement (T)

* HIV-1/2 antibody

* Serum protein electrophoresis (SPE)

CASE STUDY (20 M) - IMMUNOLOGY (DAY 3)

* Monospot test Negative

* RPR Negative

* Antinuclear antibody (ANA) Negative

* Complement (T) 48 U/mL [31 – 66 U/mL]

* HIV-1/2 antibody Invalid

* Serum protein electrophoresis Severe hypogammaglobulinemia

PRINCIPLES OF HIV-1/2 ANTIBODY TEST

* Lateral flow immunochromatographic procedure

* Antigens and antibody immobilized onto nitrocellulose membrane in T and C zones

* Test (T) Zone * Synthetic peptides from HIV envelope region

* Control (C) Zone* Goat anti-human IgG

* Developer solution * Facilitates flow of specimen onto test strip* Rehydrates protein-A gold colorimetric reagent

CASE STUDY (20 M) – IMMUNOLOGY (DAY 4)

Patient Reference

* Immunoglobulin A (IgA) < 15.0 81 - 463 mg/dL

* Immunoglobulin G (IgG) < 60.0 694 - 1618 mg/dL

* Immunoglobulin M (IgM) < 5.0 48 - 271 mg/dL

CASE STUDY (20 M) – DIFFERENTIAL DIAGNOSIS

* Bruton’s X-linked agammaglobulinemia (XLA)

* Common variable immunodeficiency (CVID)

* Severe combined immunodeficiency (SCID)

* Omenn syndrome (OS)

CASE STUDY (20 M) - MOLECULAR PATHOLOGY (FLOW CYTOMETRY)

Patient Reference

* CD3+/CD5+ 79% 52 – 84%

* CD4 lymphocytes 45% 30 – 61%

* CD8 lymphocytes 30% 12 – 42%

* CD19+/CD20+ 18% 5 – 25%

* CD3-/CD56+ 3% 5 – 30%

CASE STUDY (20 M) –FLOW CYTOMETRY

Percent Cells/uL Reference* Lymphs (CD45) 1540 1000 - 4800

* T-Lymphs (CD3) 1175 690 – 2540

* % T-Lymphs 76 55 – 84 (CD3/CD45)

* T-Helper lymphs 687 410 – 1590 (CD3+CD4)

* %T-Helper lymphs 45 31 – 60 (CD3+CD4/CD45)

CASE STUDY (20 M) – CLINICAL MANIFESTATION (DAY 5)

* Herpetiform vesicles on erythematous base* Side of head

* Lower lip

* External ear

* CN V3 herpes zoster reactivation

CASE STUDY (20 M) – DISCHARGE DIAGNOSES (DAY 5)

* Pneumococcal meningitis with bacteremia

* Pseudomonas aeruginosa otitis externa

* Common variable immunodeficiency (CVID)

* CN V3 herpes zoster reactivation

COMMON VARIABLE IMMUNODEFICIENCY (CVID)

* Most prevalent primary immunodeficiency

* Heterogeneous group of immunologic disorders

* Unknown etiology

* Characterized by marked deficiency of* IgG and IgA* IgM and T-cell dysfunction* Generalized lymphadenopathy and splenomegaly

CVID – PATHOPHYSIOLOGY

* Number of mechanisms for defective antibody production

* B-cell defects* Differentiation of B-cells into plasma cells

* T-cell defects* Low level expression of CD40 ligand

CVID – EPIDEMIOLOGY

* Prevalence of 1 case in 10,000 to 50,000 population

* Female to male ratio of 1

* All races

* Age at diagnosis* 1 to 5 years* 16 to 20 years* 21 years and greater (60%)

CVID – COMPLICATIONS AND RISKS

* Recurrent infections* Upper and lower respiratory tract

* Streptococcus pneumoniae and Haemophilus influenzae* Herpes labialis (HSV)* Herpes zoster (VCV)

* Autoimmune diseases (RA, AHA, ATP)

* Malignancy * Non-Hodgkin’s lymphoma* Malignant lymphoma