Figure 2. Relative 2′′dichlorofluorescein (DCF) fluorescence. CYS decreased intracellular ROS levels in a dose-dependent manner (p<0.001; Kruskal–Wallis test). PHA-stimulated PBMCs served as the positive control and unstimulated PBMCs served as the negative control. *: statistically significant by the Mann–Whitney U test.