Characterization of the Potentiation Effect of Activin on Human Erythroid Colony Formation In Vitro

Activin, also named FSH-releasing protein, was previously shown to induce hemoglobin accumulation in K562 cells and potentiate the proliferation and differentiation of CFU-E in human bone marrow cultures Present studies indicate that the potentiation effect of activin is lineage specific In addition to CFU-E, activin caused an increase in the colony formation of BFU-E from either bone marrow or peripheral blood It had little effect on the colony formation of CFU-GM and the mixed colonies from CFU-GEMM In serum-depleted culture, the effect of activin was shown to be dose-dependent with doses effective at picomolar concentrations The potentiation effect of activin was exerted indirectly through mediation of both monocytes and T lymphocytes Activin was also found to increase specifically the proportion of DNA-synthesizing erythroid progenitors from both bone marrow and peripheral blood It had little effect on DNA synthesis in CFU-GM and in mitogen-stimulated lymphocytes Addition of the monocytes or T lymphocytes to their respective depleted subpopulations of mononuclear cells reconstituted the enhancing effect of activin on the colony formation and DNA synthesis of erythroid progenitors These results strongly suggest a specific role of activin in potentiating the proliferation and differentiation of erythroid progenitors in vitro