Granulocyte colony-stimulating factor promotes functional maturation of O2- generating system during differentiation of HL-60 cells to neutrophil-like cells

The effects of granulocyte colony-stimulating factor (G-CSF) on development of O-2(-) generating system during differentiation of HL-60 cells to neutrophil-like cells have been studied. G-CSF enhanced O-2(-) generating ability of HL-60 cells whose differentiation had been initiated by dimethylsulfoxide (DMSO) or retinoic acid (RA), The O-2(-) generations by the differentiated HL-60 cells in response to opsonized zymosan (OZ), formyl-Met-Leu-Phe (fMLP), and IgG-coated zymosan were increased two- to fourfold as a result of incubation of the cells undergoing the differentiation with G-CSF, The potentiation by G-CSF occurred in a dose-dependent manner with the maximum effect at about 10 ng/ml G-CSF. The effect of G-CSF could not be fully explained by up-regulation of the receptor expression on the HL-60 cells, because the number of C3bi receptors was not altered by G-CSF, whereas the expression of fMLP receptor was enhanced by G-CSF. On the other hand, the O-2(-) generation of the differentiated cells activated by phorbol 12-myristate 13-acetate was not affected by the G-CSF treatment, suggesting that the biochemical events in the cells after PKC activation might not be enhanced by G-CSF, Assuming that the signaling pathways linking OZ or fMLP receptor might be enhanced by G-CSF, alteration in the cellular sn-1,2-diacylglyceroIs (DAG) level upon stimulation with OZ or fMLP was compared between the G-CSF-treated and nontreated cells. Whereas DAG level was not increased by the stimulation in the cells treated with DMSO alone, a significant increase in DAG;level upon the stimulation was observed in the cells treated with G-CSF and DMSO, These results suggest that G-CSF would enhance the organization of a receptor-linked DAG generating system in the differentiating cells, leading the cells to generate more O-2(-). (C) 1998 Academic Press.