Tryptase is a neutral serine protease stored in mast cell granules. Release of tryptase from the secretory granules is characteristic of allergic and inflammatory reactions. Serum tryptase concentration is increased 1–6 hours after severe anaphylactic reaction caused by drugs, latex, insect venoms or foods. Some drugs as opiates, aspirin and salicylates in foods can cause direct tryptase release from the mast cells and cause anaphylactoid reactions. Anaphylactic reactions are characterised also by increase in total IgE and specific IgE in response to a causing allergen.
High level of tryptase is found also in the sera of patients after fatal anaphylactic reaction. High baseline serum tryptase was ascertained in allergic patients with a history of severe sting reaction, which indicates high risk of anaphylactic reaction. Baseline tryptase is increased also in mastocytosis, especially in its systemic form. Serum tryptase measurements can be used as one parameter to distinguish anaphylactic reactions from other systemic disturbances such as cardiogenic shock, in evaluating the risk of severe sting reaction and in the diagnostics of mastocytosis.