Bleomycin-stimulated hamster alveolar macrophages release interleukin-1

The capacity of alveolar macrophages (AM) of bleomycin-instilled hamsters to proliferate mouse thymocytes (interleukin-1 activity) and hamster fibroblasts (fibroblast proliferation (FP) activity was studied. Using bleomycin-instilled hamsters, the FP activity of AM culture supernatants was increased significantly on days 1, 5, and 10 after instillation of bleomycin. The interleukin-1 (IL-1) activity, however, was increased significantly on day 1 only as compared with saline-treated hamsters. Next, normal AM were stimulated in vitro by bleomycin. After being fractionated by chromatography, their culture supernatant showed IL-1 activity, which also indicated FP activity. These results suggest that bleomycin directly stimulates AM to release IL-1 in the fibrogenic responses.