Demonstration of a free elastolytic metalloenzyme in human lung lavage fluid and its relationship to alpha 1-antiprotease.

Although the human alveolar macrophage in tissue culture can secrete an elastolytic metalloenzyme that is not inactivated by alpha1-antiprotease (AAP), levels of this proteolytic activity and its relationship to AAP in human lung lavage fluid (HLF) are unknown from previous studies. Therefore, we measured elastolytic activity in concentrated (20- to 30-fold) HLF from 15 smokers and 10 nonsmokers and related results to measurements of AAP in these fluids. Activity (mean ± SEM) against a 14C elastin substrate (expressed as nanograms of porcine pancreatic elastase equivalents per milligram of lavage fluid protein) in smokers, 18.9 ± 6.7, significantly exceeded (p = 0.05) levels present in nonsmokers, 4.4 ± 1.8. With the synthetic elastin-like chromophore substrate succinyl-trialanine-nitroanilide (SLAPN), activity in individual samples was reduced 79% by EDTA, a metalloproteinase inhibitor, whereas activity was reduced by only 29% in the presence of PMSF, a serine proteinase inhibitor. In addition, using a p...