[Influence of macrophage culture supernatants on erythroblastic islets in rat erythropoiesis].

The isolation of central macrophages from erythroblastic islands (EI) permitted analysis of the role of EI macrophage factors in erythropoiesis. EI macrophage supernatant and peritoneal macrophage supernatant both had a similar effect on erythropoiesis. They exerted an erythropoietin-like effect. We observed changes in the number of erythroblasts per island; their distribution within each island during the maturation process was described. The role of the central macrophage in EI was discussed. We suggested a direct transfer of an erythropoietin-like activity to the erythroblasts which increases the efficacy of stimulation.