Micro & Immunology · single question
Contact dermatitis is classified as which type of hypersensitivity reaction?
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Correct answer: B. Type IV (delayed, T-cell mediated)
- A. Incorrect. Type I (immediate) hypersensitivity is IgE-mediated — examples: anaphylaxis, allergic rhinitis, urticaria.
- B. Correct. Contact dermatitis is a classic Type IV (DELAYED-TYPE) hypersensitivity reaction, mediated by sensitized T-lymphocytes (not antibodies). The 24–72 hour delay after antigen exposure is characteristic. Examples: latex allergy, poison ivy, nickel allergy, dental material reactions.
- C. Incorrect. Type III (immune complex) involves antigen-antibody complex deposition — examples: serum sickness, lupus nephritis.
- D. Incorrect. Type II (cytotoxic) involves IgG/IgM antibodies against cell surface antigens — examples: hemolytic anemia, pemphigus vulgaris.
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