Granulocytic and monocytic differentiation of CD34hi cells is associated with distinct changes in the expression of the PU.1-regulated molecules, CD64 and macrophage colony-stimulating factor receptor.
The present study investigated the possibility that macrophage colony-stimulating factor (M-CSF) responsiveness of hematopoietic progenitor cells is regulated at the level of receptor expression and that M-CSF receptor (M-CSFR) may be used as an early marker of monocyte lineage commitment. Immunofluorescence measurements with an anti-M-CSFR antibody showed that 44% +/- 5% of CD34hi cells expressed the receptor. The M-CSFR was present on progenitor cells that were positive for the granulo-monocytic marker CD64, but not on primitive, erythroid, or lymphoid progenitors. The CD34hiCD64+ population could be divided into subsets of M-CSFRhi and M-CSFRlo cells. In addition, a subset of CD34hiCD64-M-CSFRhi cells was found. CD34+ cells that were positive for M-CSFR, CD64, or both gave rise exclusively to granulo-monocytic cells, and 65% of the granulomonocytic colony-forming cells in the CD34+ population were recovered from these cells. Approximately 70% of the colony-forming cells (CFCs) derived from CD34hiM-CSFRhi cells were macrophage colony-forming units (CFU-M), whereas 91% of the CFCs in the CD34hiCD64+M-CSFRlo population were granulocyte colony-forming units (CFU-G). The M-CSFRhi cells with the highest frequency of colony-forming and bipotent cells and largest average colony size were found in the CD64- subset, indicating that M-CSFR appears earlier than CD64 during monocyte development. After 60 hours in culture, a subset of the CD34hiM-CSFRhi cells had downmodulated M-CSFR (29% to 38%). This population gave rise almost exclusively to granulocytes, whereas the cells that remained M-CSFRhi gave rise exclusively to monocytes. In all experiments, the M-CSFRhi population responded to M-CSF, whereas minimal responses were observed among M-CSFRlo cells. These results suggest that M-CSF target specificity among human hematopoietic progenitor cells is determined by lineage-specific regulation of the M-CSFR and show that M-CSFR is a useful marker to discriminate between monocytic and granulocytic progenitor cells.
Becton Dickinson Immunocytometry Systems, San Jose, CA 95131-1807, USA.
J
J
Olweus
P A
PA
Thompson
F
F
Lund-Johansen
D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001853:Bone Marrow / Q000196:embryology; D002454:Cell Differentiation; D019070:Cell Lineage; D003114:Colony-Forming Units Assay; D005786:Gene Expression Regulation; D006098:Granulocytes / Q000166:cytology*; D006412:Hematopoietic Stem Cells / Q000145:classification / Q000166:cytology* / Q000187:drug effects; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D009000:Monocytes / Q000166:cytology*; D011518:Proto-Oncogene Proteins / Q000502:physiology*; D051381:Rats; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000235:genetics; D017452:Receptors, IgG / Q000096:biosynthesis* / Q000235:genetics; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1
D018952:Antigens, CD34; D016173:Macrophage Colony-Stimulating Factor; D011518:Proto-Oncogene Proteins; D016186:Receptor, Macrophage Colony-Stimulating Factor; D017452:Receptors, IgG; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1