FIGURE 4.
Sequential exposure of undifferentiated monocytic cells to low non-apoptotic concentrations of Vpr causes apoptosis. Primary monocytes (1.0 × 106/ml) were treated first with a non-apoptotic dose of 0.5 μm Vpr for 2 h, followed by a second low dose of 0.25 or 0.5 μm Vpr for another 2 h. THP1 cells (1.0 × 106/ml) were treated first with a non-apoptotic dose of 0.5 μm Vpr for 24 h, followed by a second low dose of 0.25 or 0.5 μm Vpr for another 24 h. Cells were then analyzed by annexin-V staining and flow cytometry for the measurement of apoptosis. Right panels show the mean percentage of apoptosis ± S.D. (error bars) of three experiments. *, p < 0.05. Histograms show one representative experiment.