Functional assay of alpha 1-antitrypsin in obstructive lung disease

A decreased concentration of alpha 1-antitrypsin is associated with a high risk for obstructive lung disease. We measured the elastase inhibitory capacity, the most important biologic measure of alpha 1-AT function, using a natural substrate. The gel plate assay that we developed uses a commercial gelatin film and is more sensitive, faster, and cheaper than similar elastin-elastase methods. In serum samples from 76 patients with emphysema, there was a high correlation between the immunologically measured alpha 1-AT and the elastase inhibitory capacity. There was no evidence for a functionally deficient alpha 1-AT in any of these patients.