[Participation of products of macrophage origin in regulating monocytopoiesis].

Products secreted by mouse peritoneal macrophages phagocytizing latex particles in monolayer culture in vitro were found to induce monocytosis in vivo. They inhibited mouse bone marrow colony formation and simultaneously stimulated the accumulation of immature macrophages in semisolid agar culture. The addition of these products to the liquid bone marrow culture resulted in reduction of proliferative activity of non-adherent cells and in increase of proliferative activity of adherent cells as revealed from 3H-thymidine uptake. The possible role of the products secreted by macrophage in feedback regulation is discussed.