Mast cells or mastocytes belong to the white blood cells (leukocytes) and are directly involved in the immune defense. The term 'mast cell' is somewhat misleading in terms of the actual function, because this is not a fat cell, but mobile, in the bloodstream and tissue circulating cell body. The discoverer Paul Ehrlich initially suspected that this cell type would provide the surrounding cells with nutrients, which is why he called them 'mast cells' (from 'fattening' or 'feeding'). Meanwhile, the role of mast cells, as part of the immune system, could be more accurately determined.
Mast cells arise from the stem cells in the bone marrow. In a cellular body mast cells possess granulessmall granules filled with messenger substances. Antibodies produced by B lymphocytes (due to an immune reaction) activate the mast cells, causing them to empty the contents of the granules into the intercellular space (exocytosis). The heparin and histamine stored in the granules enhances the immune response as follows:
heparin: controls the speed of blood clotting. The more heparin the mast cells release, the more the blood coagulation is inhibited. In the case of cuts and wounds, this mechanism rinses out the pathogens that have entered the wound as a result of the injury.
histamine: triggers inflammation in the injured tissue. The resulting accelerated blood flow facilitates the fight against pathogens, as now clearly more immune cells flow through the tissue.