Stimulation of nonlymphoid mesenchymal cell proliferation by a macrophage-derived growth factor

Cultured mouse peritoneal macrophages secrete a growth-promoting activity that stimulates 3 types of nonlymphoid mesenchymal cells in vitro: fibroblasts, vascular smooth muscle, and vascular endothelium. Production of this macrophage-derived growth factor (MDGF) is directly related to the number of viable macrophages and their time in culture, and is independent of platelet- or plasma-derived serum growth factors. Treatment of cultured macrophages with latex, bacterial lipopolysaccharide, or phorbol myristate acetate results in increased growth factor activity. Preliminary biochemical characterization of MDGF indicates that it is a heat labile (100°C, 2 min), non-dialyzable protein, which contains at least 1 essential disulfide bond. Growth-promoting activity is not adsorbed by CM-Sephadex chromatography, under conditions that effectively remove platelet-derived growth factor(s). Serine protease activity is not required for the action of MDGF. Secretion of macrophage-derived growth factor may be relevant to the function of mononuclear phagocytes in several pathologic processes, including the neovascularization and fibroplasia of wound healing, smooth muscle hyperplsia in atherosclerosis, and proliferative glomerulonephritis.