REGULATION OF MYELOPOIESIS INVITRO - PARTIAL REPLACEMENT OF COLONY-STIMULATING FACTORS BY TUMOR-PROMOTING PHORBOL ESTERS

Abstract

Tumor-promoting phorbol esters such as 12-0-tetradecanoyl-phorbol-13-acetate (TPA) or phorbol-12,13-didecanoate (PDD) stimulate freshly isolated murine bone marrow cells in vitro to form colonies of myeloid cells in semisolid medium without added colony-stimulating factors (CSF), while phorbol and its nonpromoting derivatives do not induce marrow colony formation. TPA-stimulated colonies are composed primarily of monocyte-macrophage cells with admixed granulocytes in some colonies, and cell dose-response curves for colony formation suggest clonal origin of the colonies. The cells forming colonies in the presence of TPA alone appear to be a subset of marrow granulocyte-macrophage colony-formi..