Effect of human recombinant granulocyte/macrophage colony-stimulating factor and native granulocyte colony-stimulating factor on clonogenic leukemic blast cells.

The effects of human recombinant granulocyte/macrophage colony-stimulating factor (GM-CSF) and human native purified granulocyte colony-stimulating factor (G-CSF) on the growth of clonogenic leukemic blast cells from eight Japanese patients with acute myeloblastic leukemia were studied, using an in vitro leukemic blast colony assay. The results showed that GM-CSF stimulated leukemic blast colony formation in all cases examined, whereas G-CSF stimulated colony formation in four of the eight cases. The maximum stimulating activity of GM-CSF on the growth of clonogenic leukemic blast cells was higher than that of G-CSF in the majority of cases, while sometimes GM-CSF and G-CSF worked synergistically. Thus, the clonogenic leukemic blast cell populations seemed to be heterogeneous with respect to their in vitro response to growth regulators.