Editing Histamine (section)

== Storage and release ==
[[Image:SMCpolyhydroxysmall.jpg|thumb|Mast cells.]]
Most histamine in the body is generated in granules in [[mast cells]] and in white blood cells (leukocytes) called [[basophils]]. Mast cells are especially numerous at sites of potential injury – the nose, mouth, and feet, internal body surfaces, and blood vessels.  Non-mast cell histamine is found in several tissues, including the [[hypothalamus]] region of the [[brain]], where it functions as a neurotransmitter.  Another important site of histamine storage and release is the [[enterochromaffin-like cell|enterochromaffin-like (ECL) cell]] of the [[stomach]].

The most important pathophysiologic mechanism of mast cell and basophil histamine release is [[immune system|immunologic]].  These cells, if sensitized by [[IgE]] [[antibody|antibodies]] attached to their [[cell membrane|membranes]], [[degranulation|degranulate]] when exposed to the appropriate [[antigen]].  Certain [[amine]]s and [[alkaloid]]s, including such drugs as [[morphine]], and [[curare]] alkaloids, can displace histamine in granules and cause its release. [[Antibiotic]]s like [[polymyxin]] are also found to stimulate histamine release.

Histamine release occurs when allergens bind to mast-cell-bound IgE antibodies. Reduction of IgE overproduction may lower the likelihood of allergens finding sufficient free IgE to trigger a mast-cell-release of histamine.