Mast cells

Mast cells are formed during blood formation in the bone marrow and belong to the white blood cells.
Mast cells play an important role in the immune defence. They are found in most tissues of the body, especially those that interact with the outside world, such as the lungs, gastrointestinal tract and skin.

When a mast cell ist activated by a trigger, it releases many mediators (chemicals that set off processes that lead to symptoms). Histamine is one of over 200 mediators that mast cells can release.

Mast cell diseases occur when these cells do not behave normally and overreact.