Mast cell mediators with emphasis on intestinal mast cells.

Mast cells occur throughout most tissues although they are more prevalent in areas which come into contact with the external environment such as the skin, lungs, and gastrointestinal tract. The physiologic role of this cell is not known; however, it has a recognized pathophysiologic role as an effector cell in immediate hypersensitivity reactions. Such mast cells, when activated by either immunologic or non-immunologic stimuli, both release and generate chemical mediators such as histamine and leukotrienes which then act on surrounding tissues. Depending upon the site of mast cell degranulation, a variety of clinical findings ensue. For example, mast cell degranulation in the lungs may lead to wheezing, while mast cell degranulation in the gastrointestinal tract may lead to vomiting and diarrhea. It is now recognized that not all mast cells are identical. The best example of this mast cell heterogeneity is found in the gastrointestinal tract. There is evidence that certain gastrointestinal mast cells both contain and generate mediators either distinct from or differing in quantity from those of mast cells found at other sites. Such observations suggest that a knowledge of these differences is required to understand gastrointestinal diseases in which mast cell activation plays a part.