The in vitro effect of asbestos on the SiO2-induced macrophage fibrogenic factor and alkaline ribonuclease

Summary Macrophages released into their culture medium factors which had both mitogenic and fibrogenic effect on the cultured granulation tissue fibroblasts. The secretion of these factors as also that of the alkaline ribonuclease was changed by the treatment of macrophages with silica. The in vitro asbestos treatment removed both the mitogenic and fibrogenic effect of the control and silica treated macrophage media. The alkaline ribonuclease activity was also totally removed from all asbestos-treated media.