title: Induction of apoptosis in myeloid progenitors by granulocyte-macrophage colony-stimulating factor.
abstract: Spontaneous apoptosis of normal purified bone marrow CD34+ cells induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) via the Fas pathway appears to be mediated by caspase-1 and caspase-8 activity. In seeking an alternative explanation for this observation, the present study examined CD34+ cell growth with different cytokines, cytokine concentrations, caspase inhibitors, cell crowding and different media. Exposure of the normal CD34+ cells to different concentrations of GM-CSF and granulocyte colony-stimulating factor (G-CSF) increased apoptosis at lower concentrations. However, these GM-CSF effects were suppressed by G-CSF. Investigation of the association between apoptosis and crowding and different media showed that: 1) G-CSF and GM-CSF are equally effective as survival factors, and 2) the percentage of apoptotic cells in liquid culture was markedly lower than that found in methylcellulose culture. Finally, immunofluorescence staining showed that Fas was expressed at 10 ng/mL GM-CSF, while Bcl-2 expression was detected at 100 ng/mL. These findings suggest that cytokine concentration, cell culture conditions, cell crowding and cell interactions all are important factors in GM-CSF-induced apoptosis.
authors.affiliation: Department of Medical Laboratory Sciences, College of Applied Medical Sciences, King Faisal University, P.O. Box 2114, Dammam 31451, Saudi Arabia. faris_alenzi@hotmail.com
authors.forename: F Q B
authors.initials: FQ
authors.lastname: Alenzi
mesh_terms: D018952:Antigens, CD34 / Q000502:physiology; D017209:Apoptosis / Q000502:physiology*; D061945:Caspase Inhibitors; D002478:Cells, Cultured; D003470:Culture Media; D016207:Cytokines / Q000502:physiology; D003609:Dactinomycin / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000502:physiology*; D006801:Humans; D023461:Myeloid Progenitor Cells / Q000502:physiology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D019014:fas Receptor / Q000032:analysis
chemical_list: D018952:Antigens, CD34; D061945:Caspase Inhibitors; D003470:Culture Media; D016207:Cytokines; C491901:FAS protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D019014:fas Receptor; D003609:Dactinomycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor