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Flashcards in Immuno - hypersensitivity Deck (12):

Anaphylactic hypersensitivity

Type I

free antigen cross-links IgE, triggers mast cell and basophil degranulation (delayed response = leukotrienes)

First and Fast

Test: skin test for specific IgE


Cytotoxic hypersensitivity

Type II - cy-two-toxic

IgM/IgG bind antigen on foreign cell, tag for destruction (phagocytosis, complement-mediated inflammation, Ab-mediated cellular dysfunction)

Direct Coombs': detect antibodies that have adhered to RBCs
Indirect Coombs': detect free serum antibodies that can adhere to RBCs


Immune complex mediated hypersensitivity

Type III (3 things! Antigen - antibody - complement)

Immune complex attract neutrophils, which release lysosomal enzymes

serum sickness - 5 days post-exposure, deposition of complexes in membranes leading to tissue damage. Now commonly caused by drugs, look for fever, urticaria, arthralgia, etc.

Arthus reaction - local subacute rxn after intradermal injection of antigen. Look for edema, necrosis, activation of complement


T-cell mediated hypersensitivity

Type IV - delayed

4 T's: T cells, Transplant rejection, TB skin test, Touching

Sensitized T cells release cytokines after stimulation by antigen. No antibodies involved!


I: Allergic/atopic disorders, anaphylaxis

Type I Anaphylactic hypersensitivity


II: antibody mediated hemolysis, Goodpasture, Graves, GB syndrome, ITP, MG, rheumatic fever

Type II Cytotoxic hypersensitivity


III: Arthus rxn, SLE, polyarteritis nodosa, PSGN (vasculitidies)

Type III Immune complex mediated hypersensitivity


IV: Contact derm, GVHD, MS, PPD (no antibodies!)

Type IV T-cell mediated hypersensitivity


Blood transfusion followed by urticaria, wheezing, fever

Allergic - Type I against plasma proteins


Blood transfusion followed by dyspnea, bronchospasm

Anaphylaxis - severe allergic rxn (breathing problems)


Blood transfusion followed by fever, headaches, chills, flushing

Febrile non-hemolytic - Type II, host antibodies against donor HLA antigens and WBCs


Blood transfusion followed by fever, hypotension, hemoglobinuria, jaundice

Acute hemolytic - Type II, intravascular/ABO incompatibility (hemoglobinuria) or extravascular/host antibody rxn (jaundice)