FIG. 11.

Effect of anti-Fas blocking MAb on apoptosis of monocytes triggered by phagocytosis of bacteria. Monocytes were preincubated for 2 h with or without anti-Fas blocking MAb ZB4 (10 μg/ml) and cultured for 18 h in the presence of S. aureus. Histogram overlay shows viability determined by PI uptake in untreated cells (dotted line), cells exposed to S. aureus (thin solid line), and anti-Fas-treated cells exposed to bacteria (bold solid line). In all three experiments, anti-Fas blocking MAb protected monocytes from apoptosis triggered by phagocytosis of S. aureus (78.2% ± 4.5% PI-positive cells in cultures exposed to S. aureus versus 19.8% ± 2.8% in cultures of monocytes preincubated with anti-Fas MAb before exposure to bacteria; P < 0.01).