Role of c-kit ligand in the expansion of human hematopoietic progenitor cells.
To test the hypothesis that the c-kit ligand plays an important role in the regulation of early events occurring during human hematopoiesis, we determined the effect of a recombinant form of c-kit ligand, termed mast cell growth factor (MGF), on the high-proliferative potential colony-forming cell (HPP-CFC) and the cell responsible for initiating long-term hematopoiesis in vitro (LTBMIC). MGF alone did not promote HPP-CFC colony formation by CD34+ DR- CD15- marrow cells, but synergistically augmented the ability of a combination of granulocyte-monocyte colony-stimulating factor (GM-CSF) interleukin (IL)-3 and a recombinant GM-CSF/IL-3 fusion protein (FP) to promote the formation of HPP-CFC-derived colonies. MGF had a similarly profound effect on in vitro long-term hematopoiesis. Repeated additions of IL-3, GM-CSF, or FP alone to CD34+ DR- CD15- marrow cells in a stromal cell-free culture system increased cell numbers 10(3)-fold by day 56 of long-term bone marrow culture (LTBMC), while combinations of MGF with IL-3 or FP yielded 10(4)- and 10(5)-fold expansion of cell numbers. Expansion of the number of assayable colony-forming unit-granulocyte-monocyte (CFU-GM) generated during LTBMC was also markedly enhanced when MGF was added in combination with IL-3 or FP. In addition, MGF, IL-3, and FP individually led to a twofold to threefold increase in HPP-CFC numbers after 14 to 21 days of LTBMC. Furthermore, the effects of these cytokines on HPP-CFC expansion during LTBMC were additive. Throughout the LTBMC, cells receiving MGF possessed a higher cloning efficiency than those receiving IL-3, GM-CSF, or FP alone. These data indicate that the c-kit ligand synergistically interacts with a number of cytokines to directly augment the proliferative capacity of primitive human hematopoietic progenitor cells.
Division of Hematology/Oncology, Indiana University School of Medicine, Indianapolis.
J
J
Brandt
R A
RA
Briddell
E F
EF
Srour
T B
TB
Leemhuis
R
R
Hoffman
D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D016207:Cytokines / Q000494:pharmacology; D004920:Erythropoiesis / Q000187:drug effects; D006684:HLA-DR Antigens / Q000032:analysis; D006410:Hematopoiesis; D016298:Hematopoietic Cell Growth Factors / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D016256:Lewis X Antigen; D011518:Proto-Oncogene Proteins / Q000502:physiology; D019009:Proto-Oncogene Proteins c-kit; D019089:Stem Cell Factor
D015703:Antigens, CD; D018952:Antigens, CD34; D016207:Cytokines; D006684:HLA-DR Antigens; D016298:Hematopoietic Cell Growth Factors; D016256:Lewis X Antigen; D011518:Proto-Oncogene Proteins; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit