A comparative study of the phenotype and proliferative capacity of peripheral blood (PB) CD34+ cells mobilized by four different protocols and those of steady-phase PB and bone marrow CD34+ cells.
Peripheral blood (PB) CD34+ cells from four commonly used mobilization protocols were studied to compare their phenotype and proliferative capacity with steady-state PB or bone marrow (BM) CD34+ cells. Mobilized PB CD34+ cells were collected during hematopoietic recovery after myelosuppressive chemotherapy with or without granulocyte-macrophage colony-stimulating factor (GM-CSF) or granulocyte colony-stimulating factor (G-CSF) or during G-CSF administration alone. The expression of activation and lineage-associated markers and c-kit gene product were studied by flow cytometry. Proliferative capacity was measured by generation of nascent myeloid progenitor cells (granulocyte-macrophage colony-stimulating factor; CFU-GM) and nucleated cells in a stroma-free liquid culture stimulated by a combination of six hematopoietic growth factors (interleukin-1 (IL-1), IL-3, IL-6, GM-CSF, G-CSF, and stem cell factor). G-CSF-mobilized CD34+ cells have the highest percentage of CD38- cells (P < .0081), but otherwise, CD34+ cells from different mobilization protocols were similar to one another in their phenotype and proliferative capacity. The spectrum of primitive and mature myeloid progenitors in mobilized PB CD34+ cells was similar to their steady-state counterparts, but the percentages of CD34+ cells expressing CD10 or CD19 were lower (P < .0028). Although steady-state PB and chemotherapy-mobilized CD34+ cells generated fewer CFU-GM at day 21 than G-CSF-mobilized and steady-state BM CD34+ cells (P < .0449), the generation of nucleated cells and CFU-GM were otherwise comparable. The presence of increased or comparable numbers of hematopoietic progenitors within PB collections with equivalent proliferative capacity to BM CD34+ cells is not unexpected given the rapid and complete hematopoietic reconstitution observed with mobilized PB. However, all four types of mobilized PB CD34+ cells are different from steady-state BM CD34+ cells in that they express less c-kit (P < .0002) and CD71 (P < .04) and retain less rhodamine 123 (P < .0001). These observations are novel and suggest that different mobilization protocols may act via similar pathways involving the down-regulation of c-kit and may be independent of cell-cycle status.
To
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Leukaemia Research Unit, Hanson Centre for Cancer Research, Institute of Medical and Veterinary Science, Adelaide, Australia.
Haylock
D N
DN
Dowse
T
T
Simmons
P J
PJ
Trimboli
S
S
Ashman
L K
LK
Juttner
C A
CA
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000032:analysis; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis; D001773:Blood Cells / Q000166:cytology*; D001854:Bone Marrow Cells; D002455:Cell Division; D003520:Cyclophosphamide / Q000494:pharmacology; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006684:HLA-DR Antigens / Q000032:analysis; D006410:Hematopoiesis / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D016130:Immunophenotyping; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D016184:Receptors, Colony-Stimulating Factor / Q000378:metabolism; D011990:Receptors, Transferrin
D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D000944:Antigens, Differentiation, B-Lymphocyte; C068126:CD71 antigen; D006684:HLA-DR Antigens; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D011990:Receptors, Transferrin; D016179:Granulocyte Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003520:Cyclophosphamide; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1