GM-CSF and G-CSF increase the uptake of dehydroascorbic acid (DHA) by human neutrophils and monocytes. (A) Time course of the effect of GM-CSF (•) and TNF (□) on the uptake of dehydroascorbic acid by human neutrophils. Cells were treated with 0.5 nmol/L GM-CSF or 1 nmol/L TNF for the time periods indicated in the figure. Uptake of dehydroascorbic acid was measured afterwards in a 5-minute assay. Data represent the mean ± SD of four samples. (B) Dose-dependence of the effect of GM-CSF (•), G-CSF (○) and TNF (□) on the uptake of dehydroascorbic acid by human neutrophils. Cells were incubated for 30 minutes in the presence of the indicated concentrations of the different agonists and uptake of dehydroascorbic acid was measured in a 5-minute assay. (C) Time course of the effect of GM-CSF (•) and G-CSF (○) on the uptake of dehydroascorbic acid by human monocytes. Cells were treated with 0.5 nmol/L GM- or G-CSF, or left untreated (controls, □), for the time periods indicated in the figure. Uptake of dehydroascorbic acid was measured afterwards in a 5-minute assay. Data represent the mean ± SD of four samples. (D) Dose-dependence of the effect of GM-CSF (•) and G-CSF (○) on the uptake of dehydroascorbic acid by human monocytes. Cells were incubated for 30 minutes in the presence of the indicated concentrations of the different agonists and uptake of dehydroascorbic acid was measured in a 5-minute assay. Data represent the mean ± SD of four samples and correspond to one of three similar experiments.