Figure 1: Effect of phototherapy on apoptosis index. Percentage of U937 cells binding annexin V after twelve hours of LPS (1 μg.mL-1) exposure was used as the apoptosis index. U937 cells were treated with staurosporine (8 μM) as a positive control for annexin V binding. One hour after LPS addition in the culture medium, the U937 cells were irradiated with phototherapy (4.5 J/cm2) during 60 seconds. Three hours after LPS addition, ROS level was measured. Results are expressed as fluorescence units. Each bar represents mean ± S.D. of three independent experiments. Statistical differences were considered when p<0.05.