Selective inhibition of primitive hemopoietic colony-forming cells by an extract from normal marrow: comparison with transforming growth factor-beta.

An extract from normal bone marrow (NBME) which inhibits proliferation of spleen colony-forming units CFU-S selectively inhibits interleukin 3 (IL-3)-driven colony formation by primitive hemopoietic progenitors. This activity is distinct from transforming growth factor-beta (TGF beta), which also inhibits development of primitive progenitors. There is evidence that the two activities inhibit proliferation of target cells by different mechanisms and that the bone marrow extract has a direct effect on cell cycling, whereas the effect of TGF beta to suppress proliferation is probably indirect.