Figure 5: Effect of phototherapy on GSH level. U937 cells were activated with LPS (1 μg.mL-1) and one hour after its addition in the culture medium the cells were treated with phototherapy (4.5 J/ cm2) during 60 seconds. In another assay, one hour before the LPS addition, U937 cells were pretreated with 20 mM N-acetylcysteine (NAC) and twelve hours after it, they were cultured in the presence of LPS. The GSH concentration was determined by fluorescence from a GSH standard. Each bar represents mean ± S.D. of three independent experiments. Statistical differences were considered when p<0.05.<0.05.