Micro & Immunology · single question
A patient takes amoxicillin for 8 days and develops urticaria, nausea, and vomiting. Which immunoglobulin is responsible for this delayed reaction?
Show answer and explanation
Correct answer: C. IgG
- A. IgA is the secretory immunoglobulin found in mucosal surfaces and saliva. It is not involved in systemic drug hypersensitivity reactions.
- B. IgM is involved in early primary immune responses and activates complement. It is not the primary mediator of drug-induced serum sickness-like reactions.
- C. IgG mediates Type II (cytotoxic) and Type III (serum sickness/immune complex) reactions. A delayed reaction appearing after 8 days of antibiotic use is consistent with an IgG-mediated immune complex (Type III/serum sickness-like) response. ✓
- D. IgE mediates immediate hypersensitivity (Type I, anaphylaxis) — occurring within minutes to hours. Urticaria at 8 days is too late for an IgE-mediated reaction.
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