Dietary supplementation with tocotrienols enhances immune function in C57BL/6 mice

{alpha-Tocopherol} {(alpha-Toc)} enhances T cell function, whereas little is known in this regard for tocotrienols {(T3),} the less-known members of the vitamin E family. We pair-fed young (4 mo) and old (23 mo) {C57BL/6} mice 0.1% Tocomin 50%, a mixture of T3 and {alpha-Toc} or a control diet containing an equal amount of {alpha-Toc} for 6 wk. As expected, lymphocyte proliferation was lower in the old mice compared with the young mice. Lymphocyte proliferation in the old T3 group was significantly higher than that in the old control group, whereas no significant difference was found in young mice. Splenocytes from old mice produced less interleukin {(IL)-2,} {IL-4,} {IL-6,} and {IL-10} compared with young mice, whereas no significant age-related difference was found in {IL-1beta,} tumor necrosis factor-alpha, and interferon-gamma. T3 feeding was associated with a higher {IL-1beta} production in old mice but not in young mice. Peritoneal macrophages from old mice produced significantly more {IL-1beta,} {IL-6,} {IL-10,} and prostaglandin E(2) {(PGE(2))} compared with those from young mice. Mice of both ages fed T3 had higher production of {IL-1beta} but not {PGE(2)} or other cytokines. In the in vitro study, splenocytes isolated from young and old mice were supplemented with the purified form of each individual T3 (0.01-10 {mumol/L)} and mitogen-stimulated cell proliferation was determined. All T3 enhanced lymphocyte proliferation in old but not young mice with a potency order of alpha- {\textgreater} gamma- {\textgreater} {delta-T3.} Together, these results suggest a beneficial effect of T3 in improving the age-related decline in T cell function.