Combination of stem cell factor and granulocyte colony-stimulating factor mobilizes the highest number of primitive haemopoietic progenitors as shownby pre-colony-forming unit (pre-CFU) assay

Fifty-two patients with poor prognosis carcinoma of the breast underwent pe ripheral blood stem cell (PBSC) mobilization using five different regimens. The yields of primitive haemopoietic progenitors were quantified by a rece ntly described pre-colony-forming unit (pre-CFU) assay using limiting dilut ion analysis (LDA). Results of days 14 and 35 pre-CFU were also correlated with conventional CD34(+) cell enumeration, CFU-GM (granulocyte-macrophage) and long-term culture-initiating cell (LTCIC) assays. The yield of pre-CFU s with the combination of granulocyte colony-stimulating factor (G-CSF) and stem cell factor (SCF) was significantly higher than with G-CSF alone, cyc lophosphamide (Cyclo) and granulocyte-monocyte colony-stimulating factor (G M-CSF), interleukin (IL)-3 and GM-CSF, or Cyclo alone. No significant corre lation between neutrophil engraftment and pre-CFU could be demonstrated. Fu rthermore, CFU-GM was shown to bear a stronger correlation with pre-CFU and LTCIC than CD34(+) cell measurement; thus, CFU-GM remains a useful biologi cal tool for haemopoietic stem cell assay. We conclude that the combination of G-CSF and SCF mobilizes the highest number of pre-CFUs as measured by f unctional pre-CFU assay, which provides an alternative measurement of primi tive haemopoietic progenitors to the LTCIC assay.