Micro & Immunology · single question
Same case (Type I allergic reaction). Which sign specifically identifies the allergic nature of the reaction?
Show answer and explanation
Correct answer: A. Rash (urticaria)
- A. Correct. Rash/urticaria/hives is the hallmark dermatologic sign of IgE-mediated Type I hypersensitivity, reflecting mast cell degranulation and histamine release.
- B. Incorrect. Nausea occurs in many conditions and is not specific to the allergic immune mechanism.
- C. Incorrect. Diarrhea can result from GI mast cell activation but is not the specific identifying marker.
- D. Incorrect. Vomiting is a non-specific GI response, not the distinctive allergic marker.
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