The effect of mononuclear phagocytes on the formation of spleen colonies in mice

Abstract

The bone marrow cells of intact CBA mice were mixed with either syngeneic bone marrow, spleen or with peritoneal macrophages or with macrophage-like J-774 cells or with human peripheral blood monocytes of healthy donors, and all mixtures were introduced into lethally X-irradiated mice. In each case, in the spleens of the recipients colonies of the predominantly myeloid type distinctly predominated. The observed effect depended on the proportion and type of the macrophages in their mixture with the bone marrow cells. Prior X-irradiation of the mice before taking their macrophages markedly decreased the observed myeloid-induced function of the peritoneal and, especially, spleen, but not bone marrow macrophages. It was found that about 50% of the CFU-S of bone marrow origin adhered to the monolayer culture of syngeneic peritoneal macrophages during 1 h of their co-incubation. These CFU-S formed spleen colonies of predominantly myeloid type when they were administered to the recipients together with the macrophages acting as carriers of CFU-S. The significance and possible mechanism of the revealed function of the mononuclear phagocyte is discussed.