Description
Histamine (β-imidazole-ethylamine), a biogenic amine, is a product of the histidine metabolism.
It is produced by decarboxylation of histidine. Histamine is widely distributed in mammalian tissues. It’s bound to heparin (as inactive form) and stored in the granules of basophilic leukocytes and mast cells and is actively released as required. These cells, if sensitized by IgE antibodies attached to their membranes, degranulate when exposed to the appropriate antigen. Histamine plays a major rule in the initial phase of an anaphylactic reaction. The quantification of histamine in plasma after allergen administration is of clinical interest. Histamine is part of the immune response to foreign pathogens, and it increases the permeability of the capillaries to white blood cells and other proteins, in order to allow them to engage foreign invaders in the affected tissues. 1-Methylhistamine is a histamine metabolite. It is a product of histamine 1-methyltransferase. Urinary histamine and 1-methylhistamine are highly correlated with histamine in plasma. Therefore, allergic reactions can be examined by determination of histamine and 1-methylhistamine in urine.
