Usefulness of serum mast cell-specific chymase levels for postmortem diagnosis of anaphylaxis.

Chymase, a serine protease, is stored mainly in secretory granules of human mast cells. Serum chymase concentration was examined in 8 autopsy cases with anaphylaxis as well as in 104 control cases without anaphylaxis. It was detected in all 8 cases with anaphylaxis (range 3-380 ng/ml, mean 89.8 ng/ml), while it was detected in only 2 of the 104 controls and was below a detectable level (<3 ng/ml) in the other 102. Serum tryptase levels are known to be a diagnostic indicator of anaphylaxis, therefore the relationship between serum chymase and tryptase levels was investigated in the 8 cases of anaphylactic death; a significant positive correlation was found (r=0.826, p=0.011). Furthermore, chymase was shown to be quite stable in serum. These results showed that measurement of serum chymase levels might be an additional tool for postmortem diagnosis of anaphylaxis.