Diseases of the Immune System

Question 1

Results from activation of TH2 CD4+ helper T cells by environmental antigens, leading to the production of IgE antibodies, which become attached to mast cells; examples: Anaphylaxis, Allergies, Bronchial asthma

Answer 1

Type I Hypersensitivity (Immediate)

Question 2

Caused by antibodies that bind to fixed tissue and cell antigens and promote phagocytosis and destruction of the coated cells or trigger pathologic inflammation in tissues; examples: Goodpasture syndrome, Autoimmune hemolytic anemia, Immune thrombocytopenia, Pemphigus vulgaris, ANCA vasculitides, Acute rheumatic fever, Graves disease, Myasthenia gravis, Insulin-resistant diabetes, Pernicious anemia, hyperacute and acute humoral rejection

Answer 2

Type II Hypersensitivity (Antibody-mediated)

Question 3

Caused by antibodies binding to antigens to form complexes that circulate and may deposit in vascular beds and stimulate inflammation secondary to complement activation; examples: SLE, serum sickness, Arthus reaction, PSAGN, PAN, Reactive arthritis

Answer 3

Type III Hypersensitivity (Immune-complex mediated)

Question 4

Cell-mediated immune responses in which T lymphocytes cause tissue injury, either by producing cytokines that induce inflammation and activate macrophages, or by directly killing cells; examples: Allergic contact dermatitis, Multiple sclerosis, Tuberculosis, PPD, RA, IBD, Acute cellular and chronic rejection, Type 1 DM and Hashimoto thyroiditis (the last two have Type 2 components as well)

Answer 4

Type IV Hypersensitivity (T-cell-mediated/delayed)

Question 5

32/F presents to the clinic with symptoms of fatigue, joint pains, and malar rash. CBC revealed anemia and low platelet count. What is the diagnosis?

Answer 5

SLE

Question 6

Hallmark of SLE.

Answer 6

Production of autoantibodies

Question 7

Mechanisms of organ damage in SLE.

Answer 7

Type III (most); Type II (opsonization, hematologic manifestations)

Question 8

Most common autoantibody in SLE.

Answer 8

ANA (98%)

Question 9

Most specific autoantibodies for SLE.

Answer 9

anti-Sm (Smith), anti-dsDNA (anti-dsDNA correlates with disease activity)

Question 10

Autoantibodies associated with congenital heart block in neonatal lupus.

Answer 10

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

Question 11

Histopathologic findings in SLE with skin involvement.

Answer 11

LM: Liquefactive degeneration of basal layer, edema at DEJ, mononuclear infiltrates around blood vessels and skin appendages IF: Deposition of Ig and complement at DEJ

Question 12

Type of LE that associated with Hydralazine, INH, Procainamide, D-Penicillamine intake; rarely involves kidneys and brain; rarely associated with anti-dsDNA; associated with anti-histone antibodies.

Answer 12

Drug-induced lupus

Question 13

Immune complexes in mesangium only; no alterations detectable by light microscopy.

Answer 13

Lupus nephritis Type I (Minimal mesangial)

Question 14

Immune complexes in mesangium with mild to moderate increase in mesangial matrix and cellularity.

Answer 14

Lupus nephritis Type II (Mesangial proliferative)

Question 15

Lesions visualized in fewer than half of the glomeruli, segmentally or globally distributed within each glomerulus; with cell proliferation, swelling, and infiltration of neutrophils and fibrinoid deposits.

Answer 15

Lupus nephritis Type III (Focal)

Question 16

Most serious form and most commonly encountered; involvement of half or more glomeruli; with diffuse hypercellularity and wire-looping due to extnsive subendothelial deposits.

Answer 16

Lupus nephritis Type IV (Diffuse)

Question 17

Widespread thickening of capillary wall due to subepithelial immune complexes.

Answer 17

Lupus nephritis Type V (Membranous)

Question 18

Complete sclerosis of greater than 90% of glomeruli; presents with end-stage renal disease.

Answer 18

Lupus nephritis Type VI (Advanced sclerosing)

Question 19

A clinicopathologic entity with a triad of dry eyes, dry mouth and other manifestations, such as arthritis.

Answer 19

Sjogren syndrome

Question 20

Most common and most important autoantibody detected in Sjogren syndrome.

Answer 20

Anti-Ro (SS-A) and anti-La (SS-B) (90%)

Question 21

Triad of 1. chronic inflammation (autoimmunity); 2. widespread damage to small blood vessels; 3. progressive interstitial and perivascular fibrosis in the skin and multiple organs.

Answer 21

Systemic sclerosis

Question 22

Most common autoantibody associated with diffuse cutaneous systemic sclerosis.

Answer 22

Anti-DNA topoisomerase I (anti-Scl 70)

Question 23

Common autoantibody associated with limited scleroderma (limited cutaneous systemic sclerosis).

Answer 23

Anti-centromere antibodies

Question 24

Most common antibody associated with scleroderma renal crisis.

Answer 24

Anti-RNA pol III (up to 50%)

Question 25

Most common extracutaneous manifestation of systemic sclerosis.

Answer 25

Raynaud phenomenon

Question 26

Most common cause of death in patients with systemic sclerosis.

Answer 26

Interstitial lung disease and pulmonary arterial hypertension

Question 27

Mixture of the features of SLE, systemic sclerosis, and polymyositis; associated autoantibody: anti-RNP particle-containing U1 RNP.

Answer 27

Mixed connective tissue disease (MCTD)

Question 28

48/M patient underwent kidney transplant suddenly developed bloody urine few hours after the procedure. Nephrectomy was done and revealed a cyanotic, mottled, and flaccid kidney and necrotic kidney cortex. There is neutrophilic accumulation in the arterioles, glomeruli, and peritubular capillaries. Glomeruli undergo thrombotic occlusion of capillaries and fibrinoid necrosis in arterial walls.

Answer 28

Hyperacute rejection

Question 29

45/F presented with signs of kidney failure 2 months after her renal transplant. Immunohistochemical staining reveals both CD4+ and CD8+ lymphocytes. Morphologic findings showed an extensive interstitial mononuclear infiltrate with edema and mild interstitial hemorrhage.

Answer 29

Acute cellular (T-cell mediated) rejection

Question 30

30/M developed oliguria and subsequent renal failure 3 weeks after an uneventful kidney transplant. Renal findings showed necrotizing vasculitis with endothelial cell necrosis, neutrophilic infiltration, deposition of complement, antibody and fibrin, and thrombosis.

Answer 30

Acute antibody-mediated rejection

Question 31

24/F diagnosed with renal failure underwent renal transplant. Four years later, increasing levels of creatinine was noted, and biopsy showed an interstitial fibrosis and tubular atrophy, glomerulopathy with duplication of basement membrane, and multilayering of peritubular capillary basement membranes. Interstitial mononuclear cell infiltrates, NK cells and plasma cells were also noted.

Answer 31

Chronic rejection

Question 32

Complication of hematopoietic stem cell transplantation, wherein immunologically competent cells attack the tissues of the immunocompromised host.

Answer 32

Graft vs. host disease

Question 33

A constellation of genetically distinct syndromes with common feature of defects in both humoral and cell-mediated immune responses, making affected infants susceptible to severe recurrent infections by bacteria, viruses, fungi, protozoans, and opportunistic infections.

Answer 33

Severe combined immunodeficiency (SCID)

Question 34

Two common patterns of inheritance of SCID, and the associated defects.

Answer 34

X-linked: common gamma chain (receptors of ILs, especially IL-7) AR: Adenosine deaminase deficiency

Question 35

Primary immune deficiency characterized by absent or markedly decreased numbers of B-cells in the circulation, with depressed serum levels of all classes of immunoglobulin.

Answer 35

X-linked agammaglobulinemia (Bruton disease)

Question 36

Cardinal features of Thymic hypoplasia (DiGeorge syndrome).

Answer 36

Cardiac defect (TOF), Abnormal facies, Thymic aplasia, Cleft palate, Hypocalcemia, 22q11.2 chromosomal deletion (CATCH 22)

Question 37

Disorder of lymphocyte activation, characterized by absence of CD40L (CD145) that results in lack of class-switching with consequent increase in IgM and decrease in IgA, IgG and IgE.

Answer 37

Hyper IgM syndrome

Question 38

An X-linked recessive disease characterized by thrombocytopenia, eczema, and marked vulnerability to recurrent infection ending in early death.

Answer 38

Wiskott-Aldrich syndrome

Question 39

Hereditary angioedema is secondary to:

Answer 39

C1 inhibitor deficiency

Question 40

Deficiency of the following complement protein increases susceptibility to infections involving pyogenic bacteria.

Answer 40

C3

Question 41

Deficiency of the following complement proteins increases susceptibility to immune complex-mediated disease.

Answer 41

C1q, C2 and C4

Question 42

Deficiency of the following complement proteins increases susceptibility to Neisseria infections.

Answer 42

C5-C9

Question 43

Most common secondary immunodeficiency; caused by HIV infection, characterized by profound immunosuppression that leads to opportunistic infections, secondary neoplasms, and neurologic manifestations; the virus targets CD4+ T cells

Answer 43

Acquired immune deficiency syndrome (AIDS)

Question 44

The hallmark of AIDS:

Answer 44

Variable loss of T-cell mediated immunity

Question 45

Cells initially infected by HIV in sexual transmission.

Answer 45

Dendritic cells

Question 46

Glycoprotein present in HIV for attachment.

Answer 46

gp120

Question 47

Glycoprotein present in HIV for fusion.

Answer 47

gp41

Question 48

Most common fungal infection in patients with AIDS.

Answer 48

Candidiasis

Question 49

Most common type of lymphoma associated with HIV infection.

Answer 49

B-cell lymphomas

Question 50

A disorder of protein misfolding, causing extracellular deposition of pink or red colored deposits stained with Congo red, with apple-green birefringence in polarized light.

Answer 50

Amyloidosis

Question 51

Most common organ affected in amyloidosis and also with the most serious involvement.

Answer 51

Kidney