Human pulmonary alveolar macrophages obtained by bronchoalveolar lavage from both normal controls and smokers secreted in vitro a neutral proteinase that degraded denatured collagens. Optimal expression of the proteinase was detected after 3-5 d of culture. The proteinase could not be detected in the media of cultures that had been treated with 0.5 micrograms/ml of cycloheximide. The gelatinase had an Mr of 90,000 and was immunologically cross-reactive with human neutrophil gelatinase. When newly synthesized 35S-methionine-labeled proteins were analyzed, the proteinase appeared to be a major secretion product of alveolar macrophages. Chromatography on gelatin-Sepharose gave a single peak of activity that was predominantly composed of the 90,000-mol-wt proteinase. The proteolytic activity in the gelatin-Sepharose-purified material was inhibited by EDTA and 1,10-phenanthroline, but not by N-ethylmaleimide or phenylmethanesulfonyl fluoride, indicating that the proteinase was a metalloproteinase. The partially purified material was also capable of degrading native type V collagen and this degradation was inhibited in the presence of an antibody to neutrophil gelatinase. The data suggest that human alveolar macrophages in culture elaborate a metalloproteinase that degrades both native type V collagen and denatured collagens.
M S Hibbs, J R Hoidal, A H Kang
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.