Mast cell tryptase and carboxypeptidase A expression in body fluid and gastrointestinal tract associated with drug-related fatal anaphylaxis.

Aim: To investigate the expression of mast cell tryptase and carboxypeptidase A in drug-related fatal anaphylaxis.

Methods: The expression of mast cell tryptase and carboxypeptidase A in 15 autopsy cases of drug-related fatal anaphylaxis and 20 normal autopsy cases were detected. First, the expression of mast cell tryptase was determined in stomach, jejunum, lung, heart, and larynx by immunofluorescence. Different tissues were removed and fixed in paraformaldehyde solution, then paraffin sections were prepared for immunofluorescence. Using specific mast cell tryptase and carboxypeptidase A antibodies, the expression of tryptase and carboxypeptidase A in gastroenterology tract and other tissues were observed using fluorescent microscopy. The postmortem serum and pericardial fluid were collected from drug-related fatal anaphylaxis and normal autopsy cases. The level of mast cell tryptase and carboxypeptidase A in postmortem serum and pericardial fluid were measured using fluor enzyme linked immunosorbent assay (FEIA) and enzyme linked immunosorbent assay (ELISA) assay. The expression of mast cell tryptase and carboxypeptidase A was analyzed in drug-related fatal anaphylaxis cases and compared to normal autopsy cases.

Results: The expression of carboxypeptidase A was less in the gastroenterology tract and other tissues from anaphylaxis-related death cadavers than normal controls. Immunofluorescence revealed that tryptase expression was significantly increased in multiple organs, especially the gastrointestinal tract, from anaphylaxis-related death cadavers compared to normal autopsy cases (46.67 ± 11.11 vs 4.88 ± 1.56 in stomach, 48.89 ± 11.02 vs 5.21 ± 1.34 in jejunum, 33.72 ± 5.76 vs 1.30 ± 1.02 in lung, 40.08 ± 7.56 vs 1.67 ± 1.03 in larynx, 7.11 ± 5.67 vs 1.10 ± 0.77 in heart, P < 0.05). Tryptase levels, as measured with FEIA, were significantly increased in both sera (43.50 ± 0.48 μg/L vs 5.40 ± 0.36 μg/L, P < 0.05) and pericardial fluid (28.64 ± 0.32 μg/L vs 4.60 ± 0.48 μg/L, P < 0.05) from the anaphylaxis group in comparison with the control group. As measured by ELISA, the concentration of carboxypeptidase A was also increased more than 2-fold in the anaphylaxis group compared to control (8.99 ± 3.91 ng/mL vs 3.25 ± 2.30 ng/mL in serum, 4.34 ± 2.41 ng/mL vs 1.43 ± 0.58 ng/mL in pericardial fluid, P < 0.05).

Conclusion: Detection of both mast cell tryptase and carboxypeptidase A could improve the forensic identification of drug-related fatal anaphylaxis.