Effect of recombinant human granulocyte colony-stimulating factor on hemopoietic cells in serum-free culture.

The effect of recombinant human erythropoietin (Ep) and granulocyte colony-stimulating factor (G-CSF) on colony formation by human hemopoietic progenitors was examined in a methylcellulose culture system. In the serum-containing culture system, granulocyte-macrophage (GM) colonies and erythroid bursts were formed by non-phagocytic mononuclear cells only in the presence of Ep. To exclude the effect of the serum, which may have hemopoietic factors, we replaced the serum with bovine serum albumin, transferrin, and lipids. In serum-free culture, recombinant Ep supported erythroid colony formation, but not erythroid burst formation. While G-CSF could support the proliferation of macrophages (30%) as well as neutrophils in the presence of fetal calf serum (FCS), it supported mainly neutrophils (97%) in serum-free culture. In this culture system, G-CSF could not induce burst formation in the presence of Ep. By using a serum-free culture system, we found that human G-CSF is a lineage-specific hemopoietic factor which acts on granulocyte-committed progenitor cells and not on early erythroid progenitor cells.