title: Synergistic action of Flt3 and gp130 signalings in human hematopoiesis.
abstract: We recently showed that c-kit signal synergizes with glycoprotein (gp)130 signal mediated by a complex of interleukin (IL)-6 and soluble IL-6 receptor (IL-6/sIL-6R) to stimulate the expansion of human primitive hematopoietic progenitor cells and erythropoietin-independent erythropoiesis. In the present study, we examined the effect of a ligand for Flt3 (FL), whose receptor tyrosine kinase is closely related to c-kit, in combination with IL-6/sIL-6R on human hematopoiesis in vitro. In serum-containing methylcellulose clonal culture of cord blood CD34(+) cells, whereas FL alone stimulated only granulocyte-macrophage (GM) colony formation, erythroid bursts and mixed colonies in addition to GM colonies were induced by FL with IL-6/sIL-6R, but not IL-6/sIL-6R alone. In suspension culture, CD34(+) cells generated a small number of myeloid cells in the presence of FL or IL-6/sIL-6R alone. However, the addition of IL-6/sIL-6R to the culture with FL induced the generation of a significant number of erythroid cells and megakaryocytes in addition to myeloid cells. The combination of FL and IL-6/sIL-6R also induced a remarkable expansion of GM colony- and erythroid burst-forming cells and multipotential progenitors, although FL or IL-6/sIL-6R alone induced the generation of only a small number of progenitors for GM colonies. The synergistic effects of FL and IL-6/sIL-6R were confirmed in serum-free clonal and suspension cultures. In addition, the addition of anti-human gp130 monoclonal antibodies abrogated the synergistic action. These results indicate that Flt3 signal, as well as c-kit signal, synergizes with gp130 signal to stimulate human myelopoiesis, erythropoiesis and megakaryopoiesis, and the expansion of primitive multipotential hematopoietic progenitor cells.
authors.affiliation: Department of Clinical Oncology, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ebihara
authors.forename: K
authors.initials: K
authors.lastname: Tsuji
authors.forename: S D
authors.initials: SD
authors.lastname: Lyman
authors.forename: X
authors.initials: X
authors.lastname: Sui
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: K
authors.initials: K
authors.lastname: Muraoka
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: R
authors.initials: R
authors.lastname: Tanaka
authors.forename: T
authors.initials: T
authors.lastname: Nakahata
mesh_terms: D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000494:pharmacology*; D018952:Antigens, CD34 / Q000378:metabolism; D002478:Cells, Cultured; D050822:Cytokine Receptor gp130; D004357:Drug Synergism; D005312:Fetal Blood / Q000166:cytology; D006410:Hematopoiesis / Q000187:drug effects*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000494:pharmacology*; D020794:Receptor Protein-Tyrosine Kinases / Q000494:pharmacology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D019947:Receptors, Interleukin-6 / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D019089:Stem Cell Factor / Q000494:pharmacology*; D051941:fms-Like Tyrosine Kinase 3
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018952:Antigens, CD34; C494199:IL6ST protein, human; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D019947:Receptors, Interleukin-6; D019089:Stem Cell Factor; D050822:Cytokine Receptor gp130; C497970:FLT3 protein, human; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3