title: Effects of interleukin-3 and c-kit ligand on the survival of various classes of human hematopoietic progenitor cells.
abstract: We examined the effects of interleukin-3 (IL-3) and c-kit ligand (KL) on the survival of differentiated hematopoietic progenitor cells (HPC), the burst-forming unit-erythroid (BFU-E); colony-forming unit-granulocyte, erythroid, monocyte, megakaryocyte (CFU-GEMM); and CFU-granulocyte-monocyte (CFU-GM) and more primitive hematopoietic cells that give rise to these progenitor cells (pre-colony-forming cells [pre-CFC]). CD34+ HLA-DR+ cells, which are highly enriched for committed HPC, and CD34+ HLA-DR- c-kit+ cells, which contain the most primitive assayable hematopoietic cells, including long-term bone marrow culture-initiating cells, high proliferative potential-CFC, the CFU-blast, and the BFU-megakaryocyte, were suspended in serum-free medium in the presence or absence of IL-3 or KL. CD34+ HLA-DR+ cells incubated under serum-free conditions or in the presence of KL for 96 hours lost greater than 90% of assayable unilineage or multilineage HPC, whereas those cells incubated in the presence of IL-3 retained 40% of the number of HPC present at time 0. The effect of IL-3 on HPC survival was most pronounced on the BFU-E and CFU-GEMM present within CD34+ HLA-DR+ cells. Addition of IL-3, but not of KL, to CD34+ HLA-DR+ cells delayed the appearance of morphologic changes and DNA fragmentation patterns associated with cell death occurring by apoptosis. CD34+ HLA-DR-c-kit+ cells were incubated under similar serum-free conditions in the presence or absence of IL-3 or KL, and the frequency of pre-CFC was determined by limiting dilution analysis. The frequency of pre-CFC in cells incubated for 48 hours in the absence of serum was similar to that of cells incubated in the presence of IL-3 and approximately doubled when CD34+ HLA-DR- c-kit+ cells were incubated in the presence of KL. Addition of KL to serum-free suspension cultures of CD34+ HLA-DR- c-kit+ cells delayed the appearance of DNA fragmentation patterns associated with apoptosis to a greater extent than did the addition of IL-3. These studies suggests that IL-3, but not KL, promotes HPC survival, whereas KL plays a greater role than IL-3 in sustaining more primitive HPC, such as pre-CFC. The effects of both cytokines in mediating HPC and primitive hematopoietic cell survival appear to be related, in part, to their ability to suppress apoptosis.
authors.affiliation: Hematology-Oncology Section, Indiana University School of Medicine, Indianapolis.
authors.forename: J E
authors.initials: JE
authors.lastname: Brandt
authors.forename: K
authors.initials: K
authors.lastname: Bhalla
authors.forename: R
authors.initials: R
authors.lastname: Hoffman
mesh_terms: D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D002470:Cell Survival / Q000187:drug effects; D006684:HLA-DR Antigens / Q000032:analysis; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology*; D006412:Hematopoietic Stem Cells / Q000187:drug effects*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000032:analysis; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases / Q000032:analysis; D016184:Receptors, Colony-Stimulating Factor / Q000032:analysis; D019089:Stem Cell Factor
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D006684:HLA-DR Antigens; D016298:Hematopoietic Cell Growth Factors; D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D016184:Receptors, Colony-Stimulating Factor; D019089:Stem Cell Factor; D019009:Proto-Oncogene Proteins c-kit; D020794:Receptor Protein-Tyrosine Kinases