A 32‑year‑old landscaper presents to clinic with an intensel…
A 32‑year‑old landscaper presents to clinic with an intensely pruritic, erythematous, and vesicular rash on both forearms. The rash began 48 hours after clearing brush in a wooded area. On exam, he has linear streaks of vesicles and papules, some weeping serous fluid. He reports that topical antihistamines have provided no relief. He has no fever or systemic symptoms. Which of the following best explains the underlying pathophysiologic mechanism of this patient’s reaction?