title: The L4F3 antigen is expressed by unipotent and multipotent colony-forming cells but not by their precursors.
abstract: Antibody L4F3 is a murine monoclonal antibody that recognizes an antigen expressed on in vitro colony-forming cells, including virtually all CFU-GM, CFU-Meg, BFU-E, and CFU-Mix. In the present study we examined whether cells that do not express the L4F3 antigen include precursors of hematopoietic colony-forming cells. Colony-forming cells were depleted from marrow by treatment with L4F3 and complement. The remaining cells generated CFU-GM, BFU-E, and CFU-Mix when cultured in the presence of irradiated adherent cell layers from long-term marrow cultures. Marrow cells not expressing the L4F3 antigen, which were separated by cell-sorting techniques, were depleted of colony-forming cells but nevertheless generated CFU-GM when cultured over irradiated adherent cell layers. These data suggest that there are marrow precursors that do not express the L4F3 antigen and that give rise to colony-forming cells of multiple types. Negative selection techniques should allow the enrichment of these precursors of colony-forming cells, thereby enabling direct studies of these immature stem cells.
mesh_terms: D000954:Antigens, Surface / Q000032:analysis*; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002454:Cell Differentiation; D002478:Cells, Cultured; D005434:Flow Cytometry; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000276:immunology*; D006801:Humans
chemical_list: D000954:Antigens, Surface