Immunomodulatory effect of DL-α-lipoic acid in aged rats.

Senescence is the result of an imbalance between free radical production and antioxidant defenses, with concomitant oxidative stress and age-dependent functional decline. This process is especially evident in the immune cells, which use free radicals in their functions and suffer a senescent deterioration probably linked to oxygen stress. We hypothesize that oxidative damage and antioxidant imbalance may play a critical role in the immune dysfunction in aging. In the present study, we investigated this hypothesis in aged rats by treatment with alpha-lipoic acid (α-LA). We studied the effect of α-LA on immune function by examining immunomodulating factors in the plasma. Then we examined oxidative damage and antioxidant defense systems in the plasma. We found out that immune dysfunction in aged animals is associated with increased oxidative damage and decreased antioxidant status and treatment with α-LA effectively elevated immune function, decreased oxidative insult and enhanced antioxidant status. These results suggest that α-LA may be effective in improving immune function in aging through decreasing oxidative damage and revitalizing antioxidants in blood. Crown