During mast cell degranulation in an immediate hypersensitivity reaction, which mediator is primarily responsible for itching, edema, and bronchoconstriction?

During mast cell degranulation in an immediate hypersensitivity reaction, which mediator is primarily responsible for itching, edema, and bronchoconstriction?

• A. Histamine.
• B. Dopamine.
• C. Acetylcholine.
• D. Serotonin.

Answer: (A)

Histamine is the principal mediator released during mast cell degranulation in an immediate hypersensitivity reaction. When mast cells release histamine, it binds to H1 receptors on vascular endothelium, increasing vascular permeability and causing edema, and it also stimulates sensory nerve endings to produce itching. In the airways, histamine acting on smooth muscle leads to bronchoconstriction. While dopamine, acetylcholine, and serotonin can influence various physiological processes, they are not the primary drivers of itching, edema, and bronchoconstriction in this context.

Histamine is the principal mediator released during mast cell degranulation in an immediate hypersensitivity reaction. When mast cells release histamine, it binds to H1 receptors on vascular endothelium, increasing vascular permeability and causing edema, and it also stimulates sensory nerve endings to produce itching. In the airways, histamine acting on smooth muscle leads to bronchoconstriction. While dopamine, acetylcholine, and serotonin can influence various physiological processes, they are not the primary drivers of itching, edema, and bronchoconstriction in this context.