Immunology USMLE Step 1 Practice Question
A 22-year-old man presents with a pruritic vesicular rash on his forearms that developed 2 days after clearing brush in the woods. Vital signs are stable (BP 118/76, HR 88, RR 16, Temp 37.2°C, SpO2 98%). Physical examination reveals linear erythematous plaques with small vesicles; no systemic lymphadenopathy is noted. Patch testing shows positive reaction to urushiol antigen. Which of the following immune mechanisms is most likely responsible for this patient's dermatitis?
Answer choices
- ACross linking of IgE on mast cells causes histamine release within minutes
- BPreformed IgG against basement membrane proteins activates complement
- CSensitized T lymphocytes release cytokines after re exposure to hapten modified skin proteinsCorrect answer
- DDirect bacterial invasion of the epidermis
- EDeposition of circulating immune complexes in dermal blood vessels
- FIgE-mediated hypersensitivity reaction to plant alkaloids triggers immediate degranulation of basophils
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