title: Prevalence of the primitive megakaryocyte progenitors (BFU-meg) in adult human peripheral blood.
abstract: The in vitro growth of early (megakaryocyte burst-forming units, BFU-meg) and late (megakaryocyte colony-forming units, CFU-meg) megakaryocyte (meg) progenitors has been evaluated in normal adult human peripheral blood (PB). All the experiments were carried out using CD34+ cells, which were assayed in a serum-free fibrinclot assay. PB BFU-meg were morphologically characterized as plurifocal aggregates containing greater than 50 cells/colony, distinct from unifocal CFU-meg, in a limiting dilution assay. At variance with PB CFU-meg, PB BFU-meg were unaffected by the complement-mediated cytotoxicity with anti-HLA-DR. The optimal source of colony-stimulating activity for PB BFU-meg growth was recombinant human interleukin 3 (rhIL-3; 100 U/ml), which supported a significantly higher number of BFU-meg in comparison with recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF; 200 U/ml, p = 0.043). Combinations of rhIL-3 (100 U/ml) plus rhGM-CSF (200 U/ml), rhIL-3 plus recombinant human interleukin 6 (rhIL-6; 100 U plus 100 U/ml) or rhIL-3 plus rhGM-CSF plus rhIL-6 (100 U plus 200 U/ml plus 100 U/ml) failed to further increase the number of PB BFU-meg with respect to rhIL-3 (100 U/ml) alone. Both PB BFU-meg and CFU-meg were markedly inhibited, in a dose-dependent fashion, by increasing doses of human purified transforming growth factor-beta 1 (TGF-beta 1) (from 0.001 to 10 ng/ml). Finally, the CFU-meg/BFU-meg ratio in PB (0.52) was significantly different from that of normal bone marrow (2.3), clearly indicating that adult human peripheral blood predominantly carries primitive megakaryocytic progenitors.
authors.affiliation: Institute of Histology and General Embryology, University of Bologna, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Zauli
authors.forename: L
authors.initials: L
authors.lastname: Vitale
authors.forename: M A
authors.initials: MA
authors.lastname: Brunelli
authors.forename: G P
authors.initials: GP
authors.lastname: Bagnara
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002999:Clone Cells; D003114:Colony-Forming Units Assay; D016895:Culture Media, Serum-Free; D003602:Cytotoxicity, Immunologic; D015672:Erythroid Precursor Cells / Q000166:cytology* / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D008533:Megakaryocytes / Q000166:cytology* / Q000187:drug effects; D010641:Phenotype; D011994:Recombinant Proteins / Q000494:pharmacology; D013234:Stem Cells / Q000276:immunology
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D016895:Culture Media, Serum-Free; D007377:Interleukin-3; D015850:Interleukin-6; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor