Distinct mouse bone marrow macrophage precursors identified by differential expression of ER-MP12 and ER-MP20 antigens

Eur J Immunol. 1994 Oct;24(10):2279-84. doi: 10.1002/eji.1830241003.


The characterization of early branch points in the differentiation of leukocytes requires identification of precursor cells in the bone marrow. Recently, we produced two monoclonal antibodies, ER-MP12 and ER-MP20, which in two-color flow-cytometric analysis divide the murine bone marrow into six defined subsets. Here we show, using fluorescence-activated cell sorting followed by macrophage colony-stimulating factor-stimulated culture in soft agar, that precursors of the mononuclear phagocyte system reside only within the ER-MP12hi20-, ER-MP12+20+ and ER-MP12-20hi bone marrow subsets. Together, these subsets comprise 15% of nucleated bone marrow cells. Furthermore, we provide evidence that the macrophage precursors present in these subsets represent successive stages in a maturation sequence where the most immature ER-MP12hi20- cells develop via the ER-MP12+20+ stage into ER-MP12-20hi monocytes.

MeSH terms

  • Animals
  • Antigens, Differentiation, Myelomonocytic / analysis*
  • Bone Marrow Cells*
  • Cell Differentiation
  • Female
  • Immunophenotyping
  • Macrophage Colony-Stimulating Factor / pharmacology
  • Macrophage-1 Antigen / analysis
  • Macrophages / cytology
  • Macrophages / immunology*
  • Mice
  • Mice, Inbred C57BL


  • Antigens, Differentiation, Myelomonocytic
  • Macrophage-1 Antigen
  • Macrophage Colony-Stimulating Factor