Mast cells contribute to inflammation by releasing which mediator?

• A. Bradykinin
• B. Histamine
• C. Prostaglandin
• D. Leukotriene

Answer: (B)

When mast cells are activated, they release histamine from their granules. This mediator acts quickly to drive inflammation by causing vasodilation and increasing vascular permeability, which leads to redness, warmth, and edema in the affected tissue. Histamine also contributes to itching through nerve endings.

Other mediators like bradykinin are generated in the plasma kallikrein-kinin system, while prostaglandins and leukotrienes come from arachidonic acid metabolism in various cells, not primarily from mast cell degranulation. This is why histamine is the best answer for what mast cells release to promote the early inflammatory response.