Diseases of the Immune System Flashcards by Jamaira Belmes

Caused by activation of TH2 CD4 helper T cells by environmental antigens —> PRODUCTION OF IgE ANTIBODIES which become attached to mast cells

anaphylaxis
bronchial asthma
allergic rhinitis
sinusitis (hay fever)
food allergies

Type I (immediate, IgE-mediated)

vascular dilation
edema
smooth muscle contraction
mucus production
tissue injury and inflammation

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caused by ANTIBODIES that bind to fixed tissues and cell antigens and promote phagocytosis and destruction of the coated cells or trigger pathologic inflammation in tissues

AIHA
Immune Thrombocytopenic Purpura
Pemphigus Vulgaris
ANCA-vasculitis
Goodpasture syndrome
Acute Rheumatic Fever
Myasthenia Graves
Insulin Resistant Diabetes
Pernicious anemia

Type II (Antibody-mediated)

phagocytosis and lysis of cells
inflammation
functional derangements w/o evidence of cell or tissue injury

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Caused by ANTIBODIES BINDING ANTIGENS TO FORM COMPLEXES that circulate and may deposit in vascular beds and stimulate inflammation secondary to complement activation

SLE
PSAGN
Polyarteritis Nodosa
Reactive arthritis
Serum sickness
Arthus reaction

Type III (Immune Complex Mediated)

inflammation
necrotizing vasculitis (fibrinoid necrosis)

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Cell mediated responses in which T LYMPHOCYTES CAUSE TISSUE INJURY either by producing cytokines that induce inflammation and activate macrophages or by directly killing cells

Rheumatoid arthritis
Multiple sclerosis
Type I DM
IBD
Psoriasis
Contact sensitivity
PPD

Type IV (T cell mediated/delayed)

perivascular cellular infiltrates
edema
granuloma formation
cell destruction

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32/F w/ DOB, bilateral elbow joint pains and rash after sun exposure. CBC showed low hemoglobin and reticulocytosis. (+) ANA titer. Diagnosis

Systemic Lupus Erythematosus (SLE)

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Mechanisms of organ damage in SLE

Type III
Type II (opsonization and phagocytosis, hematologic manifestations)

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MC autoantibody in SLE

ANA

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MOST SPECIFIC autoantibodies for SLE

anti-Sm (Smith)
anti-dsDNA - correlates w/ disease activity

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Histopathologic findings in SLE w/ skin involvement

LM: liquefactive degeneration of basal layer
edema of DEJ
mononuclear infiltrates around blood vessels and skin apppendages

IF: deposition of IG and complement at DEJ

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Type of LE associated w/ HYDRALAZINE, INH, POCAINAMIDE and D-PENICILLAMINE intake, rarely associated w/ anti-dsDNA

Associated w/ ANTI-HISTONE antibodies

Drug-Induced Lupus

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34/F, w/ DRY EYES and DRY MOUTH. Lip biopsy shows ACINAR ATROPHY, FIBROSIS and HYALINIZATION of the minor salivary glands

Diagnosis

Sjogren syndrome (late)

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MC and most important autoantibody detected in Sjogren syndrome

Anti-Ro (SS-A)
Anti-La (SS-B)

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45/F with CHRONIC GERD, hx of PROGRESSIVE DYSPNEA and CKD with noted THICKENING OF THE SKIN

Diagnosis

Systemic Sclerosis(Scleroderma)

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MC autoantibody associated w/ DIFFUSE CUTANEOUS SYSTEMIC SCLEROSIS

anti-DNA topoisomerase I (anti-Scl 70)

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Common autoantibody associated w/ LIMITED SCLERODERMA (limited cutaneous systemic sclerosis)

Anti-centromere antibodies

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48/M, s/p kidney transplant suddenly developed BLOODY URINE few hrs after the procedure. Nephrectomy revealed a CYANOTIC, MOTTLED and FLACCID KIDNEY w/ NECROTIC CORTEX. Biopsy shows THROMBOTIC OCCLUSION OF THE CAPILLARIES and FIBRINOID NECROSIS OF ARTERIAL WALLS.
Diagnosis

Hyperacute Rejection

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45/F w/ signs of RENAL FAILURE 2 mos AFTER her RENAL TRANSLANT. Biopsy shows EXTENSIVE INTERSTITIAL MONONCULEAR INFILTRATE w/ edema and mild interstitial hemorrhage.

(+) CD3, CD4 and CD8

Acute cellular (T cell mediated) rejection, Tubuloinerstitial type (tubulitis)

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30/M, developed OLIGURIA and SUBSEQUENT RENAL FAILURE 3 WEEKS AFTER an un uneventful kidney transplant. Biopsy shows INFLAMMATION OF GLOMERULI and PERITUBULAR CAPILLARIESw/ FOCAL THROMBOSIS OF SMALL VESSELS.

Diagnosis

Acute Antibody-mediated Rejection

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24/F, diagnosed w/ renal failure underwent renal transplant. 4 years later, INCREASING LEVEL OF CREATININE was noted. Biopsy. shows INTERSTITIAL FIBROSIS and TUBULAR ATROPHY.

Diagnosis

Chronic Rejection

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66/M, known case of MULTIPLE MYELOMA underwent HSC transplantation presented w/ BLOODY DIARRHEA and GENERALIZED MORBILIFORM RASH FEW WEAKS after the procedure.

Diagnosis

Acute graft VS host disease (GVHD)

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Few years after HSC transplantation developd cutaneous sclerosis, jaundice and dysphagia. Barium swallow showed ESOPHAGEAL STRICTURES.

Diagnosis

Chronic GVHD

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6 mos/M, w/ MORBILIFORM RASH, RECURRENT ORAL THRUSH, DIAPER RASH and FAILURE TO THRIVE.
PE: (-) CERVICAL LYMPHADENOPATHY
CXR: (-) thymic shadow

Diagnosis

Severe Combined Immunodeficiency (SCID)

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7 mos/M, w/ UNREMARKABLE 1st 6 MOS of LIFE, RECURRENT PNEUMONIA and STEATORRHEIC DIARRHEA.
Sputum Culture: H. influenzae
Fecalysis: Giardia lamblia trophozoites
PE: (-) cervical lymphadenopathy
LOW serum Igs

X-Linked Agammaglobulinemia ( Bruton disease)

4 mos/ M, CYANOSIS since BIRTH associated w/ COARSE FACIAL FEATURES and CLEFT PALATE presented w/ RECURRENT VIRAL INFECTIONS.
PE: +3 reflexes
CXR: boot shaped heart (-) thymic shadow
FISH: (+) deletion of Ch22q11.2 locus

Diagnosis

DiGeorge syndrome

8 mos/M, history of ECZEMATOUS DERMATITIS and RECURRENT INFECTIONS. CBC: low platelet Diagnosis

Wiskott-Aldrich Syndrome (x-liked recessive)

16/F, with HISTORY OF VIRAL URTI 3 weeks prior, developed RECURRENT UTI and AGE. Low serum IgA Diagnosis

Isolated IgA deficiency (acquired)

MC secondary immunodeficiency caused by HIV infection PROFOUND IMMUNE DEFICIENCY - HALLMARK Opportunistic infections, secondary neoplasms and neurologic manifesations CD4 T cells

Acquired Immune Deficiency Syndrome (AIDS)

MC fungal infection in patients w/ AIDS

Candidiasis

MC type of lymphoma associated w/ HIV infection

B-cell lymphoma

AIDS-DEFINING SARCOMA caused by Human Herpesvirus 8 (HHV8) Typified by appearance of PURPLE PATCHES, PLAQUES or NODULES on the SKIN

Kaposi Sarcoma

Common Autoimmune Diseases and HLA types involved

HLA-B27 - ankylosing spondylitis and RA HLA-DR,DQ - type I DM and multiple sclerosis HLA-DQ2, DQ8 - Celiac disease HLA-DR4 - RA HLA-DQ - SLE

TRIAD of Sjogren Syndrome

dry eyes (keratoconjunctivitis sicca) dry mouth (xerostomia) autoimmune mediated destruction of lacrimal gland and salivary glands

MC associated autoimmune disease in Sjogren syndrome

Rheumatoid Arthritis

TRIAD of Systemic Sclerosis (Scleroderma)

chronic inflammation (autoimmunity) widespread damage to small blood vessels progressive interstitial and perivascular fibrosis in the skin and multiple organs

CREST SYNDROME

Calcinosis Raynaud phenomenon Esophageal dysmotility Sclerodactyly Telangiectasia

Autoantibodies in scleroderma associated with HIGHER risk for pulmonary fibrosis and peripheral vascular disease

Anti-Scl 70 (anti-DNA topoisomerase I)

Defect in migration and chemotaxis of phagocytes LATE SEPARATION OF UMBILICAL CORD recurrent skin and mucosal bacterial infection ABSENT PUS

Leukocyte Adhesion Deficiency (LAD) AR defect expression of INTEGRIN CD18

Defect in migration and chemotaxis of phagocytes LATE SEPARATION OF UMBILICAL CORD recurrent skin and mucosal bacterial infection ABSENT PUS

Leukocyte Adhesion Deficiency (LAD) AR defect expression of INTEGRIN CD18

Defect in LYST gene -- problem in PHAGOLYSOSOME FUNCTIONING ALBINISM neurodegeneration recurrent pyogenic infections

CHEDIAK HIGASHI SYNDROME AR

Defect in MICROBICIDAL activity Deficiency of NADPH OXIDASE Severe, persistent and chronic pyogenic infections caused by catalase POSITIVE bacteria

Chronic Granulomatous Disease XR

Primary Immunodeficiency (Genetic Defects) INNATE IMMUNITY (Granulocytes)

Leukocyte Adhesion Deficiency (LAD) CHEDIAK HIGASHI SYNDROME Chronic Granulomatous Disease

Primary Immunodeficiency (Genetic Defects) ADAPTIVE IMMUNITY (Lymphocytes)

SCID X-linked (Bruton) Agammaglobulinemia Thymic aplasia (CATCH 22)

Absent or markedly decreased B cells in circulation, depressed serum Ig levels (ALL CLASSES) ABSENT PLASMA CELLS RECURRENT BACTERIAL AND ENTEROVIRAL INFECTIONS AFTER 6 mos

X-linked (Bruton) Agammaglobulinemia XR underdeveloped germinal centers of lymph nodes, Peyer patches, appendix and tonsils

Defective IL-2 receptor gamma chain ADENOSINE DEAMINASE DEFICIENCY SMALL THYMUS (-) lymphoid cells HYPOPLASTIC lymphoid tissues failure to thrive, chronic diarrhea, thrush

SEVERE COMBINED IMMUNODEFICIENCY (SCID)

22q11 microdeletion failure to develop 3rd and 4th pharyngeal pouches ABSENT THYMUS (no thymic shadow on CXR) ABSENT PARATHYROID GLANDS LOW T cells in blood and lymphoid tissues

Thymic aplasia (CATCH 22) CATCH Cardiac defects (conotruncal abnormalities) Abnormal facies Thymic hypoplasia Cleft palate Hypocalcemia d.t. parathyroid aplasia

Triad of Wiskott Aldrich Syndrome WAS gene mutation --> combined B and T cell disorder associated with SMALL PLATELETS

Thrombocytopenia Infection Eczema

MC secondary immunodeficiency

AIDS

Hallmark of AIDS

Profound immune deficiency

Most abundant viral antigen and is widely used to diagnose HIV

protein p24

ATTACHES to CD4 -- conformation change -- new recognition site of CXCR4 and CCR5 -- gp120 binds to CXCR4 and CCR5

gp120

FUSION PROTEIN -- integrates itself into host cell membrane -- facilitates fusion and delivery of viral genome

gp41

Acute retroviral syndrome

flu-like illness rash cervical adenopathy diarrhea vomiting

Phase of CLINICAL LATENCY - few or no clinical manifestations Slow but steady decline in CD4+T cell counts Increasing viral load

CHRONIC PHASE (AIDS) 7-10 yrs

Dramatic increase in viral load Opportunistic infections, secondary neoplasms, CNS disease

AIDS typical phase length (from onset to death) - 2-3 years

MC and most serious form of organ involvement in amyloidosis

KIDNEY

Major organ involved in senile systemic amyloidosis

HEART