A patient with a known shellfish allergy accidentally ingests shrimp. Which mechanism primarily explains why systemic vasodilation and bronchoconstriction occur?

💡 Explanation

Systemic vasodilation and bronchoconstriction in shellfish allergy result from mast cell degranulation, because IgE antibodies bound to mast cells cross-link upon shrimp antigen exposure, triggering histamine release. Therefore, histamine increases vascular permeability and smooth muscle contraction, rather than neutrophil chemotaxis, complement activation, or macrophage cytokine production.

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