[Clonal response of murine myelomonocytic leukemia cells (WEHI-3B-Y1) to purified recombinant human hemopoietic factors in serum-free culture].

We tested purified recombinant hemopoietic factors for their effects on the proliferation and differentiation of murine myelomonocytic leukemia cells (WEHI-3B-Y1) in serum-free agar culture. We found that purified recombinant human G colony-stimulating factor (CSF) markedly increased the colony number of WEHI-3B-Y1 cells and differentiation-inducing activity. However, at low colony densities [( 100/dish), G-CSF did not induce the differentiation of WEHI-3B-Y1 cells. We conclude that G-CSF does not induce the differentiation of WEHI-3B-Y1 cells directly, but induce the differentiation as a result of the secondary autoinduction of differentiation. Interleukin 3 (IL-3) slightly enhanced but erythropoietin (Epo) did not alter the colony number of WEHI-3B-Y1 cells. GM-CSF or M-CSF decreased the colony number of WEHI-3B-Y1 cells. Such purified recombinant human IL-3, Epo, GM-CSF and M-CSF did not induce morphologically the distinct differentiation of WEHI-3B-Y1 cells.