Carboxypeptidase Is Marker for Anaphylaxis

A new study has determined that carboxypeptidase could be a serum marker for anaphylaxis episodes.

Current anaphylaxis assays are based on the measurement of tryptase, an enzyme released by mast cells during severe allergic reactions. This test fails to detect a significant number of patients at risk. A different enzyme, carboxypeptidase, is released preferentially by mast cells during an episode of anaphylaxis.

Anaphylaxis is a severe acute allergic reaction that can be fatal if not recognized and treated swiftly. Andrew F. Walls, Ph.D., University of Southampton (UK) and colleagues looked for a mast cell product that is uniformly elevated and more specific than tryptase in patients with acute sensitivity reactions. They generated specific monoclonal antibodies to carboxypeptidase and developed a sandwich-based enzyme-linked immunoabsorbant assay (ELISA) that can detect the enzyme in vitro. They then adapted the lab test into a clinical-style study and used it to measure carboxypeptidase levels in patients and healthy controls.

The researchers found that carboxypeptidase levels were significantly higher in people who had an anaphylactic reaction compared to people without a reaction. In 83% of the anaphylaxis cases with an elevated level of tryptase, carboxypeptidase levels were also elevated. Their most important finding was that in 77 out of 110 cases (70%) of suspected anaphylaxis there was an elevated level of carboxypeptidase but no elevated level of tryptase in the serum.

"Our feeling is that this is going to be a useful new laboratory test for anaphylaxis” observed Dr. Wallis. This would mean that when patients arrive in an emergency department there would be a better test available to prove that they are suffering from anaphylaxis, and not from another condition that causes a skin reaction or respiratory problems.



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