[Anti-inflammatory effects of histamine]

Most of the body's histamine is stored in the granules of tissue mast cells and blood basophils. Free histamine regulates gastric acid secretion, acts as a neurotransmitter in the central nervous system and is a potent mediator of allergic inflammation. Histamine may also exert negative influences on human inflammatory cells in vitro. Evidence is provided here that the administration of histamine in man may depress the chemotactic response of the PMNs and spontaneous or pulsed T-lymphocyte proliferation. Thus, histamine has indeed, in man, some antiinflammatory actions which may explain the increased sensitivity of asthmatics to respiratory infections.