What do mast cells release in response to infections and allergens?

Mast cells play a crucial role in the immune response, especially during allergic reactions and infections. Upon activation, mast cells primarily release histamine, a chemical that contributes to the inflammatory response. Histamine increases the permeability of blood vessels, allowing immune cells and proteins to enter tissues more easily, which is essential for combating infections and dealing with allergens.

While cytokines and other molecules are important in various aspects of the immune response, histamine is specifically linked to the immediate hypersensitivity reactions. It is this release of histamine that leads to symptoms such as swelling, redness, and itchiness associated with allergies.

In contrast, antibodies are produced by B cells and complement proteins are part of the complement system that enhances the ability to clear pathogens, but neither is directly released by mast cells in response to infections or allergens.