What role does histamine play in the body's response to allergens?

Histamine plays a crucial role in the body's immune response, particularly when dealing with allergens. When the body encounters an allergen, histamine is released from mast cells and basophils, which are types of immune cells. The release of histamine leads to a series of physiological changes that contribute to the symptoms associated with allergic reactions.

Specifically, histamine triggers inflammation and causes a variety of allergic symptoms, such as itching, swelling, redness, and increased mucus production. It does this by binding to specific receptors on blood vessels, resulting in vasodilation (widening of the blood vessels) and increased permeability of the vessel walls. This allows more immune cells and fluids to access the affected tissues, which is part of the body's attempt to eliminate the allergen.

In summary, the correct answer highlights histamine's central role in initiating the inflammatory response and facilitating the hallmark symptoms of allergies, making it a key mediator in the allergic response.