Effect of c-kit ligand on in vitro human megakaryocytopoiesis.
An evaluation of the effects of a recombinant, soluble form of the c-kit ligand alone and in combination with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) on the regulation of human megakaryocytopoiesis was performed using a serum-depleted clonal assay system and a long-term bone marrow culture system. The effects of the c-kit ligand on the primitive megakaryocyte (MK) progenitor cell, the burst-forming unit-megakaryocyte (BFU-MK), and the more differentiated colony-forming unit-megakaryocyte (CFU-MK) were determined. The c-kit ligand alone had no megakaryocyte colony-stimulating activity (MK-CSA) but was capable of augmenting the MK-CSA of both GM-CSF and IL-3. The range of synergistic interactions of c-kit ligand varied with the class of MK progenitor cell assayed. In the case of the BFU-MK, the c-kit ligand synergistically augmented the numbers of colonies formed in the presence of IL-3, but not GM-CSF, but increased the size of BFU-MK-derived colonies cloned in the presence of both of these cytokines. However, at the level of the CFU-MK, c-kit ligand synergized with both GM-CSF and IL-3 by increasing both colony numbers and size. Although the c-kit ligand alone exhibited limited potential in sustaining long-term megakaryocytopoiesis in vitro, it synergistically augmented the ability of IL-3, but not GM-CSF, to promote long-term megakaryocytopoiesis. These data indicate that multiple cytokines are necessary to optimally stimulate the proliferation of both classes of MK progenitor cells and that the c-kit ligand plays a significant role in this process by amplifying the MK-CSA of both GM-CSF and IL-3.
Briddell
R A
RA
Department of Medicine, Indiana University School of Medicine, Indianapolis.
Bruno
E
E
Cooper
R J
RJ
Brandt
J E
JE
Hoffman
R
R
D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D003114:Colony-Forming Units Assay; D016207:Cytokines / Q000494:pharmacology; D004357:Drug Synergism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006684:HLA-DR Antigens / Q000032:analysis; D006410:Hematopoiesis / Q000187:drug effects*; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007377:Interleukin-3 / Q000494:pharmacology; D008533:Megakaryocytes / Q000166:cytology*; D019089:Stem Cell Factor
D015703:Antigens, CD; D018952:Antigens, CD34; D016207:Cytokines; D006684:HLA-DR Antigens; D016298:Hematopoietic Cell Growth Factors; D007377:Interleukin-3; D019089:Stem Cell Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor