The Production of Committed Hemopoietic Colony - Forming Cells

Murine fetal liver cells have been fractionated by fluorescence-activated cell sorting into two fractions termed. for convenience, the pre-CFC and CFC (colony-forming cell) fractions. which differ in their relative binding of the lectin. pokeweed mitogen. The CFC fraction contained a high frequency of CFC (26%) and in liquid cultures stimulated with colony-stimulating factors generated large numbers of differentiated progeny. Consequently. residual CFC could not be detected in such cultures after day 4. In contrast. the pre-CFC fraction contained relatively few CFC (1 %) but contained the majority of CFU-S and was able to generate large numbers of new CFC after 5-7 days in liquid culture. This production of CFC from precursor cells was absolutely dependent on factors present in pokeweedmitogen-stimulated spleen cell conditioned medium (PWMSCM) or postendotoxin serum (ES) but was not stimulated by known granulocyte or macrophage colony-stimulating factors. CFC production occurred from multipotential pro-