ANTINEUTROPHIL ELASTASE ACTIVITY IN CYSTIC-FIBROSIS SERUM

The antigenic concentrations of alpha-1-antitrypsin (alpha-1AT) were measured in 13 patients with cystic fibrosis (CF) and in 11 healthy subjects. Serum alpha-1AT was purified by immunoaffinity chromatography and the antielastase activity of the purified alpha-1AT was determined by measuring the molar ratio necessary to inhibit human neutrophil elastase (HNE). The association rate constant of alpha-1AT with HNE was determined in a timed assay. The capacity of CF serum alpha-1AT to form complexes with porcine pancreatic elastase was studied by polyacrylamide gel electrophoresis. Antigenic concentrations of alpha-1-AT mu-mol/L were markedly increased in the serum of all patients with CF (61.9 +/- 4.3-mu-mol/L) in comparison to a reference standard (36.7 +/- 1.8-mu-mol/L; P < 0.0001). CF serum alpha-1AT was fully active against HNE, and its associated rate constant in the presence of HNE was similar to that of healthy subjects. In addition, CF serum alpha-1AT formed complexes with porcine pancreatic elastase that were electrophoretically indistinguishable from those of normal serum alpha-1AT. These results indicate that patients with CF have increased serum alpha-1AT concentrations and that this antiprotease, when purified from serum, functions normally.