Hypersensitivity and Autoimmunity · USMLE Step 1

A patient develops hives, bronchospasm, and hypotension minutes after eating peanuts. Which hypersensitivity reaction is this?

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

Correct answer: Type I

Type I hypersensitivity is IgE-mediated and causes immediate reactions such as anaphylaxis. Mast cell degranulation leads to rapid symptoms.

Difficulty: Medium Question 1 of 20

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