Antioxidants, cytokines, and influenza infection in aged mice and elderly humans

The age-associated dysregulation of the immune response contributes to higher incidences of infectious diseases in the aged. Of note, there is dysregulation of cytokines, including a change in T helper (Th) 1/Th2 cytokine balance and an increase in production of proinflammatory cytokines. Synthesis of many cytokines is influenced by changes in the cellular oxidant/antioxidant balance. Because vitamin E supplementation reduces oxidative stress and improves the immune response in the aged, a series of experiments was conducted to determine the effect of supplementation with vitamin E and other antioxidants on resistance to influenza infection in aged mice and the role of cytokines in vitamin E-induced increase in resistance to influenza infection. The results of these studies plus findings by other investigators on the effects of age and antioxidants on production of cytokines in human and animal models are reviewed.