Time course for the effect of TNF-α on apoptosis in human neutrophils. Human neutrophils (5 × 106/mL) were incubated in MDM containing 10% autologous serum alone (▧), or in the presence of 25 ng/mL TNF-α (▪) or 50 U/mL GM-CSF (□) at 37°C. At the time periods indicated, the cells were resuspended and cytocentrifuge preparations made. These were fixed, stained, and percent apoptosis assessed morphologically. (A) Represents the effects of TNF-α after 3, 6, 12, and 20 hours of incubation with the results from a separate series of experiments over a 1- to 8-hour time course shown in (B). The comparative effects of GM-CSF on neutrophil apoptosis at 6 and 20 hours are shown in (C). All values represent mean ± SEM of n = 3 separate experiments, each performed in triplicate (*P < .05 compared with time-matched controls). Where not shown, SEM values are less than 2% of means.
