Start practicing

Micro & Immunology · patient case question

Anaphylaxis is which type of hypersensitivity reaction?

Patient case: Hypersensitivity, asthma and research design

Scenario: Three items.

  1. Type IV
  2. Type II
  3. Type I
  4. Type III
Show answer and explanation

Correct answer: C. Type I

  • A. Type IV is delayed and cell-mediated, taking 48 to 72 hours. Contact dermatitis to nickel or latex and the tuberculin skin test are the examples.
  • B. Type II is antibody-mediated cytotoxicity — IgG or IgM directed at cell-surface antigens, as in transfusion reactions and pemphigus vulgaris.
  • C. Correct. Type I is the immediate, IgE-mediated reaction. Antigen cross-links IgE on mast cells and basophils, which degranulate and release histamine within minutes.
  • D. Type III is immune complex deposition, seen in serum sickness and lupus.

Note: Latex allergy is worth separating carefully: the dangerous immediate reaction is Type I, while contact dermatitis to glove chemicals is Type IV.

Practice Micro & Immunology questions Micro & Immunology study notes

More Micro & Immunology practice questions