Immunology - Immune Responses Flashcards

Question

Type III hypersensitivity * Reaction * Serum sickness * Arthus reaction * Test

Answer 1

* Immune complex * Antigen-antibody (IgG) complexes activate complement, which attracts neutrophils * Neutrophils release lysosomal enzymes. * **In type _III_ reaction, imagine an immune complex as _3_ things stuck together: antigen-antibody-complement.** * **Serum sickness** * An immune complex disease (type III) in which antibodies to the foreign proteins are produced (takes 5 days). * Immune complexes form and are deposited in membranes, where they fix complement (leads to tissue damage). * More common than Arthus reaction. * Most serum sickness is now caused by drugs (not serum) acting as haptens. * Fever, urticaria, arthralgias, proteinuria, lymphadenopathy 5–10 days after antigen exposure. * **Arthus reaction** * A local subacute antibody-mediated hypersensitivity (type III) reaction. * Intradermal injection of antigen induces antibodies, which form antigen-antibody complexes in the skin. * Characterized by edema, necrosis, and activation of complement. * Antigen-antibody complexes cause the Arthus reaction. * Test * Immunofluorescent staining.

Answer 2

* Delayed (T-cell-mediated) type * Sensitized T lymphocytes encounter antigen and then release lymphokines * Leads to macrophage activation * No antibody involved * Cell mediated * Therefore, it is not transferable by serum. * **_4th_ and _last_—delayed.** * Test * Patch test, PPD. * **_4_ _T_’s** * **_T_** lymphocytes * **_T_**ransplant rejections * **_T_**B skin tests * **_T_**ouching (contact dermatitis).

Answer 3

* **_ACID_** * **_A_**naphylactic and **_A_**topic (_type I_) * **_C_**ytotoxic (antibody mediated) (_type II_) * **_I_**mmune complex (_type III_) * **_D_**elayed (cell mediated) (_type IV_)

Answer 4

* Type I * Examples * Anaphylaxis (e.g., bee sting, some food/drug allergies) * Allergic and atopic disorders (e.g., rhinitis, hay fever, eczema, hives, asthma) * Presentation * Immediate, anaphylactic, atopic * Type II * Examples * Autoimmune hemolytic anemia * Pernicious anemia * Idiopathic thrombocytopenic purpura * Erythroblastosis fetalis * Acute hemolytic transfusion reactions * Rheumatic fever * Goodpasture syndrome * Bullous pemphigoid * Pemphigus vulgar * Presentation * Disease tends to be specific to tissue or site where antigen is found * Type III * Examples * SLE * Polyarteritis nodosa * Poststreptococcal glomerulonephritis * Serum sickness * Arthus reaction (e.g., swelling and inflammation following tetanus vaccine) * Presentation * Can be associated with vasculitis and systemic manifestations * Type IV * Examples * Multiple sclerosis * Guillain-Barré syndrome * Graft-versus-host disease * PPD (test for M. tuberculosis) * Contact dermatitis (e.g., poison ivy, nickel allergy) * Presentation * Response is delayed and does not involve antibodies (vs. types I, II, and III)

Answer 5

* Allergic reaction * _P_: Type I hypersensitivity reaction against plasma proteins in transfused blood. * _C_: Urticaria, pruritus, wheezing, fever. * Treat with antihistamines. * Anaphylactic reaction * _P_: Severe allergic reaction. * IgA-deficient individuals must receive blood products that lack IgA. * _C_: Dyspnea, bronchospasm, hypotension, respiratory arrest, shock. * Febrile nonhemolytic transfusion reaction * _P_: Type II hypersensitivity reaction. * Host antibodies against donor HLA antigens and leukocytes. * _C_: Fever, headaches, chills, flushing. * Acute hemolytic transfusion reaction * _P_: Type II hypersensitivity reaction. * Intravascular hemolysis (ABO blood group incompatibility) or extravascular hemolysis (host antibody reaction against foreign antigen on donor RBCs). * _C_: Fever, hypotension, tachypnea, tachycardia, flank pain, hemoglobinemia (intravascular), jaundice (extravascular hemolysis).

Answer 6

* Anti-ACh receptor * Myasthenia gravis * Anti-basement membrane * Goodpasture syndrome * Anti-cardiolipin, lupus anticoagulant * SLE, antiphospholipid syndrome * Anticentromere * Limited scleroderma (CREST syndrome) * Anti-desmoglein * Pemphigus vulgaris * Anti-dsDNA, anti-Smith * SLE * Anti-glutamate decarboxylase * Type 1 diabetes mellitus * Anti-hemidesmosome * Bullous pemphigoid * Antihistone * Drug-induced lupus * Anti-Jo-1, anti-SRP, anti-Mi-2 * Polymyositis, dermatomyositis * Antimicrosomal, antithyroglobulin * Hashimoto thyroiditis * Antimitochondrial * 1° biliary cirrhosis * Antinuclear antibodies * SLE, nonspecific * Anti-Scl-70 (anti-DNA topoisomerase I) * Scleroderma (diffuse) * Anti-smooth muscle * Autoimmune hepatitis * Anti-SSA, anti-SSB (anti-Ro, anti-La) * Sjögren syndrome * Anti-TSH receptor * Graves disease * Anti-U1 RNP (ribonucleoprotein) * Mixed connective tissue disease * c-ANCA (PR3-ANCA) * Granulomatosis with polyangiitis (Wegener) * IgA antiendomysial, IgA anti-tissue transglutaminase * Celiac disease * p-ANCA (MPO-ANCA) * Microscopic polyangiitis, Churg-Strauss syndrome * Rheumatoid factor (antibody, most commonly IgM, specific to IgG Fc region), anti-CCP * Rheumatoid arthritis

Answer 7

* B-cell vs. T-cell deficiencies * B-cell deficiencies tend to produce recurrent bacterial infections * T-cell deficiencies produce more fungal and viral infections. * Bacteria * _No T cells_: Sepsis * _No B cells_: Encapsulated (**_SHiNE_ _SK**_i_**S_**) * **_S_**treptococcus pneumoniae * **_H_**aemophilus **_i_**nfluenzae type B * **_N_**eisseria meningitidis * **_E_**scherichia coli * **_S_**almonella * **_K_**lebsiella pneumoniae * Group B **_S_**trep * _No granulocyte_: Staphylococcus, Burkholderia cepacia, Serratia, Nocardia * _No complement_: Neisseria (no membrane attack complex) * Virus * _No T cells_: CMV, EBV, JCV, VZV chronic infection with respiratory/GI viruses * _No B cells_: Enteroviral encephalitis, poliovirus (live vaccine contraindicated) * Fungi/parasites * _No T cells_: Candida, PCP * _No B cells_: GI giardiasis (no IgA) * _No granulocyte_: Candida, Aspergillus

Answer 8

* Type of disorder * B-cell disorder * Defect * Defect in **_B_**TK, a tyrosine kinase gene --\> no **_B_** cell maturation. * X-linked recessive (increase in **_B_**oys). * Presentation * Recurrent bacterial and enteroviral infections after 6 months (decrease maternal IgG). * Findings * Normal CD19+ B cell count, decreased pro-B, decreased Ig of all classes. * Absent/scanty lymph nodes and tonsils.

Answer 9

* Type of disorder * B-cell disorder * Defect * Unknown. * Most common 1° immunodeficiency. * Presentation * Majority **_A_**symptomatic. * Can see **_A_**irway and GI infections, **_A_**utoimmune disease, **_A_**topy, **_A_**naphylaxis to Ig**_A_**-containing products. * Findings * IgA \< 7 mg/dL with normal IgG, IgM levels.

Answer 10

* Type of disorder * B-cell disorder * Defect * Defect in B-cell differentiation. * Many causes. * Presentation * Can be acquired in 20s–30s * Increased risk of autoimmune disease, bronchiectasis, lymphoma, sinopulmonary infections. * Findings * Decreased plasma cells * Decreased immunoglobulins.

Answer 11

* Type of disorder * T-cell disorder * Defect * 22q11 deletion * Failure to develop 3rd and 4th pharyngeal pouches --\> absent thymus and parathyroids. * Presentation * Tetany (hypocalcemia), recurrent viral/fungal infections (T-cell deficiency), conotruncal abnormalities (e.g., tetralogy of Fallot, truncus arteriosus). * Findings * Decreased T cells, decreased PTH, decreased Ca2+. * Absent thymic shadow on CXR. * 22q11 deletion detected by FISH.

Answer 12

* Type of disorder * T-cell disorder * Defect * Decreased Th1 response. * Autosomal recessive. * Presentation * Disseminated mycobacterial and fungal infections * May present after administration of BCG vaccine. * Findings * Decreased IFN-γ.

Answer 13

* Type of disorder * T-cell disorder * Defect * Deficiency of Th17 cells due to STAT3 mutation --\> impaired recruitment of neutrophils to sites of infection. * Presentation * **_FATED_**: coarse **_F_**acies, cold (noninflamed) staphylococcal **_A_**bscesses, retained primary **_T_**eeth, increased Ig**_E_**, **_D_**ermatologic problems (eczema). * Findings * Increased IgE, decreased IFN-γ.

Answer 14

* Type of disorder * T-cell disorder * Defect * T-cell dysfunction. * Many causes. * Presentation * Noninvasive Candida albicans infections of skin and mucous membranes. * Findings * Absent in vitro T-cell proliferation in response to Candida antigens. * Absent cutaneous reaction to Candida antigens.

Answer 15

* Type of disorder * B- and T-cell disorder * Defect * Several types including defective IL-2R gamma chain (most common, X-linked), adenosine deaminase deficiency (autosomal recessive). * Presentation * Failure to thrive, chronic diarrhea, thrush. * Recurrent viral, bacterial, fungal, and protozoal infections. * Treatment: bone marrow transplant (no concern for rejection). * Findings * Decreased T-cell receptor excision circles (TRECs). * Absence of thymic shadow (CXR), germinal centers (lymph node biopsy), and T cells (flow cytometry).

Answer 16

* Type of disorder * B- and T-cell disorder * Defect * Defects in ATM gene --\> DNA double strand breaks --\> cell cycle arrest. * Presentation * Triad: cerebellar defects (**_A_**taxia), spider **_A_**ngiomas (telangiectasia), Ig**_A_** deficiency. * Findings * Increased AFP. * Decreased IgA, IgG, and IgE. * Lymphopenia, cerebellar atrophy.

Answer 17

* Type of disorder * B- and T-cell disorder * Defect * Most commonly due to defective CD40L on Th cells = class switching defect * X-linked recessive. * Presentation * Severe pyogenic infections early in life * Opportunistic infection with Pneumocystis, Cryptosporidium, CMV. * Findings * Increased IgM. * Decreased IgG, IgA, IgE.

Answer 18

* Type of disorder * B- and T-cell disorder * Defect * Mutation in WAS gene (X-linked recessive) * T cells unable to reorganize actin cytoskeleton. * Presentation * **_WATER_**: **_W_**iskott-**_A_**ldrich: **_T_**hrombocytopenic purpura, **_E_**czema, **_R_**ecurrent infections. * Increased risk of autoimmune disease and malignancy. * Findings * Decreased to normal IgG, IgM. * Increased IgE, IgA. * Fewer and smaller platelets.

Answer 19

* Type of disorder * Phagocyte dysfunction * Defect * Defect in LFA-1 integrin (CD18) protein on phagocytes * Impaired migration and chemotaxis * Autosomal recessive. * Presentation * Recurrent bacterial skin and mucosal infections, absent pus formation, impaired wound healing, delayed separation of umbilical cord (\>30 days). * Findings * Increased neutrophils. * Absence of neutrophils at infection sites.

Answer 20

* Type of disorder * Phagocyte dysfunction * Defect * Defect in lysosomal trafficking regulator gene (LYST). * Microtubule dysfunction in phagosome-lysosome fusion * Autosomal recessive. * Presentation * Recurrent pyogenic infections by staphylococci and streptococci, partial albinism, peripheral neuropathy, progressive neurodegeneration, infiltrative lymphohistiocytosis. * Findings * Giant granules in neutrophils and platelets. * Pancytopenia. * Mild coagulation defects.

Answer 21

* Type of disorder * Phagocyte dysfunction * Defect * Defect of NADPH oxidase --\> decreased reactive oxygen species (e.g., superoxide) and absent respiratory burst in neutrophils * X-linked recessive. * Presentation * Increased susceptibility to catalase (+) organisms (**_PLACESS_**): **_P_**seudomonas, **_L_**isteria, **_A_**spergillus, **_C_**andida, **_E_**. coli, **_S_**. aureus, **_S_**erratia. * Findings * Abnormal dihydrorhodamine (flow cytometry) test. * Nitroblue tetrazolium dye reduction test is (-) (test out of favor).

Answer 22

* Autograft * From self. * Syngeneic graft * From identical twin or clone. * Allograft * From nonidentical individual of same species. * Xenograft * From different species.

Answer 23

* Onset * Within minutes * Pathogenesis * Pre-existing recipient antibodies react to donor antigen (type II reaction), activate complement. * Features * Widespread thrombosis of graft vessels --\> ischemia/necrosis. * Graft must be removed.

Answer 24

* Onset * Weeks to months * Pathogenesis * Cellular: CTLs activated against donor MHCs. * Humoral: similar to hyperacute, except antibodies develop after transplant. * Features * Vasculitis of graft vessels with dense interstitial lymphocytic infiltrate. * Prevent/reverse with immunosuppressants.

Answer 25

* Onset * Months to years * Pathogenesis * Recipient T cells perceive donor MHC as recipient MHC and react against donor antigens presented. * Both cellular and humoral components. * Features * Irreversible. * T-cell and antibody-mediated damage. * Organ specific: * Heart—atherosclerosis. * Lungs—bronchiolitis obliterans. * Liver—vanishing bile ducts. * Kidney—vascular fibrosis, glomerulopathy.

Answer 26

* Onset * Varies * Pathogenesis * Grafted immunocompetent T cells proliferate in the immunocompromised host and reject host cells with “foreign” proteins --\> severe organ dysfunction. * Features * Maculopapular rash, jaundice, diarrhea, hepatosplenomegaly. * Usually in bone marrow and liver transplants (rich in lymphocytes). * Potentially beneficial in bone marrow transplant for leukemia (graft-versus-tumor effect).

Immunology - Immune Responses Flashcards

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