Histamine is secreted by basophils and mast cells as part of a local immune response to the presence of invading bodies. The basophils and mast cells are found in nearby connective tissue.This histamine release causes capillaries to become more permeable to white blood cells and other proteins, which proceed to target and attack foreign bodies in the affected tissue. Aside from humans, histamine is found in virtually all animals.y Dr Ananya Mandal, MD. Histamine is an amine that is produced as part of a local immune response to cause inflammation.