Effect of endotoxin on the production of colony-stimulating factor by human monocytes and macrophages

Colony-stimulating factor (CSF) is necessary for the clonal growth of human bone marrow in vitro. Human blood monocytes and macrophages produce CSF. Endotoxin was found to increase the level of CSF generated by macrophages, but had no stimulatory effect on monocytes. Several other substances known to influence the pinocytic or phagocytic activity of mononuclear phagocytes failed to enhance cellular CSF generation.