High-frequency granuloid colony-forming ability of G-CSF receptor possessing CD34 antigen positive human umbilical cord blood hematopoietic progenitors.

The presence of granulocyte colony-stimulating factor receptor (G-CSFR) in CD34+ hematopoietic progenitors is demonstrated by flow cytometry. Cord blood mononuclear cells (MNCs) contain about 1.09 +/- 0.2% CD34+ cells, 0.32 +/- 0.1% CD34+/G-CSFR+ (G-CSFR+) cells, and 0.77 +/- 0.1% CD34+/G-CSFR- (G-CSFR-) cells. The colony-forming ability of G-CSFR+ cells in the presence of G-CSF, granulocyte-macrophage CSF (GM-CSF), interleukin-3 (IL-3), and erythropoietin (Epo) was higher than that of G-CSFR- cells (29.5 vs. 9.8%; p < 0.01). In the fraction of G-CSFR+ cells, the most frequently formed colony type was CFU-G/GM, while burst-forming unit-erythroid (BFU-E) or colony-forming unit-macrophage (CFU-M) were rare. On the other hand, the incidence of BFU-E and CFU-G/GM was similar in the fraction of G-CSFR- cells. This indicates that most granuloid colonies of CD34+ cells were derived from G-CSFR+ cells. These results suggest a lineage commitment for the vast majority of G-CSFR+ hematopoietic progenitors.