Mast cells, which are granulocytes found in peripheral tissue, play a central role in inflammatory and immediate allergic reactions. Beta-Tryptase is a neutral serine protease and is the most abundant mediator stored in mast cell granules. The release of beta-tryptase from the secretory granules is a characteristic feature of mast cell degranulation. Mast cell beta-tryptase has an important role in inflammation and serves as a marker of mast cell activation. Beta-Tryptase activates the protease activated receptor type 2. It is involved in airway homeostasis, vascular relaxation and contraction, gastrointestinal smooth muscle activity and intestinal transport, and coagulation. Serum mast cell beta-tryptase concentration is increased in anaphylaxis and in other allergic conditions.