The clonal proliferation of normal mouse hematopoietic cells: Enhancement and suppression by colony-stimulating factor combinations

Abstract

Combinations of relatively high concentrations of the four colony-stimulating factors (CSFs) in cultures of normal mouse bone marrow cells stimulated subadditive responses in the number of colonies developing but, with some combinations, superadditive increases in mean cell numbers per colony. This latter effect was due largely to the induced development of small numbers of giant colonies containing macrophages with or without granulocytes. However, in cultures including a combination of granulocyte-macrophage-CSF (GM-CSF) with macrophage-CSF (M-CSF), a selective reduction in the number of pure macrophage colonies was observed together with a change in the morphology of those colonies that d..