Micro & Immunology · single question
What type of hypersensitivity reaction is this?
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Correct answer: A. Type I (IgE-mediated)
Type I hypersensitivity is IgE-mediated (immediate). First exposure sensitizes → IgE binds mast cells. Re-exposure → cross-linking → histamine + mediator release → bronchoconstriction, urticaria, anaphylaxis. Type II = cytotoxic (hemolytic anemia). Type III = immune complex (serum sickness). Type IV = delayed T-cell (contact dermatitis). Anaphylaxis = Type I.
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