Tryptases are serine proteases implicated in asthma and are highly expressed in human mast cells. They are derived from at least 4 nonallelic genes clustered on chromosome 16p13.3: TPSAB1, which represents the alpha and beta-I tryptase alleles; TPSB2, which represents the beta-II and beta-III tryptase alleles; TPSG1; and TPSD1. Elevated levels of serum tryptase occur in both anaphylactic and anaphylactoid reactions, but a negative test does not exclude anaphylaxis. Tryptase is less likely to be elevated in food allergy reactions as opposed to other causes of anaphylaxis.
