Effects of human alpha-interferon on granulocyte-macrophage progenitor cells (CFU-GM) in vitro.

Two preparations of human interferon (IFN)-alpha were assessed for their influence on granulocyte-macrophage progenitor cells (CFU-GM) in vitro. Both highly purified human IFN-alpha Ly and recombinant IFN-alpha 2a suppressed CFU-GM colony formation in a dose-dependent manner using low-density bone-marrow target cells. Suppression of CFU-GM colony formation was accompanied by an increase in clusters. However, depletion of monocytes, T lymphocytes and B lymphocytes from low-density bone-marrow cells resulted in insensitivity of progenitor cells to IFN-alpha. These results demonstrate that the effects of human IFN-alpha on myeloid progenitor cells (CFU-GM) are mediated by accessory cells within the bone marrow.