What triggers the release of histamine during an allergic reaction?

Histamine is released during an allergic reaction primarily through basophils, which are a type of white blood cell involved in the immune response. When an allergen is encountered, basophils are activated and degranulate, releasing histamine into the surrounding tissues. Histamine plays a crucial role in the inflammatory response, causing symptoms such as swelling, redness, and itchiness by increasing blood vessel permeability and dilating blood vessels.

The other cell types mentioned do not primarily release histamine in an allergic response. Eosinophils are typically involved in combating parasitic infections and also play a role in allergic reactions but do not release histamine as a primary function. Platelets are primarily involved in blood clotting and have a different role in the immune response, while neutrophils are the first responders to sites of infection and participate in phagocytosis, but they do not release histamine. Thus, basophils are the key players in triggering this important aspect of the allergic response.