Pharmacology · single question
A patient taking antibiotics for a while — what type of hypersensitivity is Stevens-Johnson Syndrome?
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Correct answer: A. Type IV (delayed, cell-mediated)
- A. Stevens-Johnson Syndrome (SJS) is a SEVERE CUTANEOUS ADVERSE REACTION classified as TYPE IV (delayed, cell-mediated) hypersensitivity. CD8+ cytotoxic T-cells attack keratinocytes expressing drug-hapten complexes, causing widespread epidermal necrosis. SJS typically appears 1-4 weeks after drug exposure. Common triggers: sulfonamides, anticonvulsants, allopurinol, NSAIDs, and beta-lactam antibiotics.
- B. Type III involves immune complex deposition — not the T-cell mediated mechanism of SJS.
- C. Type II involves antibody-mediated cytotoxicity — not the T-cell mediated mechanism of SJS.
- D. Type I hypersensitivity is IgE-mediated, occurring within minutes — anaphylaxis, urticaria. SJS is NOT Type I.