Hypersensitivity and Autoimmunity · USMLE Step 1

A patient develops hemolytic anemia after receiving penicillin. The drug binds to RBCs, forming a target for antibodies. Which mechanism is involved?

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

Correct answer: Type II hypersensitivity

Penicillin acts as a hapten, triggering Type II antibody-mediated destruction of RBCs. Complement contributes to hemolysis.

Difficulty: Medium Question 5 of 20

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