title: Characterization and quantitation of primitive hematopoietic progenitor cells present in peripheral blood autografts.
abstract: In this report, we assess the content of primitive hematopoietic progenitor cells (HPC) that circulate transiently in the peripheral blood (PB) of cancer patients (group A) who received a PB stem-cell-mobilizing regimen that included high-dose chemotherapy (HD-CTX) of 7 g/m2 cyclophosphamide followed by a combination of recombinant hematopoietic growth factors (C-HGF), including either interleukin-3 (IL-3) plus granulocyte-colony stimulating factor (G-CSF), IL-3 plus granulocyte-macrophage colony-stimulating factor (GM-CSF), or a recombinant GM-CSF/IL-3 fusion protein (PIXY-321). These data were compared to the HPC content of PB obtained from a similar group of cancer patients that had not received such a mobilization regimen (group B). Monoclonal antibody staining and fluorescence-activated cell sorting (FACS) were used to identify and isolate cell populations enriched for more differentiated HPC (CD34+HLA-DR+) and more primitive HPC (CD34+HLA-DR-). The content of CD34+HLA-DR+ and CD34+HLA-DR- cells in the PB of group A patients was significantly greater than that observed in the PB of group B patients. In addition, HD-CTX plus C-HGF mobilization resulted in the appearance of greater numbers of PB colony-forming units-granulocyte/macrophage, -granulocyte/erythroid/macrophage/megakaryocyte, and -megakaryocyte (CFU-GM, CFU-GEMM, and CFU-Mk), and burst-forming units-erythroid and -megakaryocyte (BFU-E and BFU-Mk) than those observed in the PB of group B patients (p < 0.01). CD34+HLA-DR- cells isolated from the PB of group A patients were capable of initiating long-term hematopoiesis in vitro, which persisted for 10 weeks, while CD34+HLA-DR- cells obtained from the PB of group B patients were capable of sustaining long-term hematopoiesis in vitro for only 4 weeks. As determined by a limiting dilution analysis of group A PB CD34+HLA-DR- cells, the frequency of cells capable of giving rise to hematopoietic progenitor cells (pre-CFC) after 2 weeks in liquid culture was 4.3% (range 1.0-8.3%). Pre-CFC constituted 0.01% (range 0.001-0.02%) of group A PB mononuclear cells, and 151 pre-CFC were calculated to be present in 1 mL mobilized PB (range 20-310/mL). These results suggest that peripheral blood mononuclear cells (PBMC) collected by leukapheresis following HD-CTX plus C-HGF mobilization contain not only differentiated HPC but also more primitive HPC.
authors.affiliation: Hematology/Oncology Section, Indiana University School of Medicine, Indianapolis.
authors.forename: J
authors.initials: J
authors.lastname: Tong
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
authors.forename: S
authors.initials: S
authors.lastname: Siena
authors.forename: E F
authors.initials: EF
authors.lastname: Srour
authors.forename: M
authors.initials: M
authors.lastname: Bregni
authors.forename: A M
authors.initials: AM
authors.lastname: Gianni
mesh_terms: D001804:Blood Transfusion, Autologous; D001943:Breast Neoplasms / Q000097:blood; D002469:Cell Separation; D002478:Cells, Cultured; D003520:Cyclophosphamide / Q000627:therapeutic use; D005260:Female; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000097:blood; D009369:Neoplasms / Q000188:drug therapy
chemical_list: D003520:Cyclophosphamide