The suppressive effects of type beta transforming growth factor (TGF beta) on primitive murine hemopoietic progenitors are abrogated by interleukin-6 and granulocyte colony-stimulating factor.

We examined the effects of type beta transforming growth factor (TGF beta) on colony formation by murine hemopoietic progenitors in methylcellulose culture. TGF beta inhibited colony formation from spleen cells of normal mice supported by interleukin-3 (IL-3) and erythropoietin (Ep). The suppressive effects of TGF beta were more profound on colony formation from cells of 5-fluorouracil (5-FU)-treated mice than those of normal mice. Addition of IL-6 or granulocyte colony-stimulating factor (G-CSF), which act synergistically with IL-3 on dormant progenitors, partially neutralized the inhibition by TGF beta of colony formation from cells of 5-FU-treated mice. We then exposed day-2 post-5-FU marrow cells to these factors for 2 days in serum-free suspension culture, washed, and replated alliquots of cells for analysis of the surviving fractions of the progenitors. While TGF beta almost totally abolished the colony-forming ability of the dormant progenitors, IL-6 and G-CSF abrogated the inhibitory effects of TGF beta. These results indicated that TGF beta and early-acting hemopoietic factors (IL-6 and G-CSF) possess counteracting effects on early progenitors.