Nickel-induced oxidative stress and effect of antioxidants in human lymphocytes

The purpose of this study was to evaluate the oxidative effect in human lymphocytes after acute nickel (Ni) treatment for 1 h; levels of intracellular reactive oxygen species (ROS), lipid peroxidation (LPO) and hydroxyl radicals ((OH)-O-.) were examined in isolated lymphocytes. The potential effects of antioxidants were also examined. After acute treatment, NiCl2 (0-10 mM) significantly decreased the viability of lymphocytes. NiCl2 appear to increase the degree of dichlorofluorescein (DCF) fluorescence and the levels of thiobarbituric acid-reactive substances (TBARS) in human lymphocytes in vitro in a concentration-dependent manner: The level of (OH)-O-. was quantified by two main hydroxylated derivates, 2,3- and 2,5-dihydroxybenzate (DHB). Levels of 2,3- and 2,5-DHB were significantly higher in the Ni-treated group than in controls. Catalase partially reduced the NiCl2-induced elevation of oxidants and TBARS, whereas superoxide dismutase (SOD) enhanced the level of oxidants and TBARS. Both NiCl2-induced fluorescence and LPO were prevented significantly by glutathione (GSH) and mannitol. NiCl2-induced increase in generation of (OH)-O-. was prevented significantly by catalase, GSH and mannitol, but not by SOD. These results suggest that NiCl2-induced lymphocyte toxicity may be mediated by oxygen radical intermediates, for which the accelerated generation of (OH)-O-. may plays an important role in Ni-induced oxidative damage of human lymphocytes. Catalase, GSH and mannitol each provides protection against the oxidative stress induced by Ni.