Vitamin E prevents the decrease of cellular immune function with aging in spontaneously hypertensive rats

This study was performed to investigate the mechanism of vitamin E (VE) induced restoration of cellular immune functions decreased with aging in spontaneously hypertensive rats (SHR). Both Wistar Kyoto rats (WKY) as control rats and SHR, 3 weeks old, were fed a diet supplemented with 50 or 585 mg VE/kg diet for 37 weeks. The changes in proportions of thymocyte subsets with aging were not significantly different between WKY and SHR. On the contrary, the expressions of both CD4 and CD8 antigens in CD4+CD8+ thymocytes were significantly reduced in SHR compared to those of WKY at the same age, which was significantly improved by taking the high VE diet at 6 or 12 weeks old. Furthermore, the production of interleukin 2 (IL2) from thymocytes was also decreased in SHR compared to WKY, which was improved by both high VE diet and in vitro treatment with indomethacin, inhibitor of PGE2 synthesis. In addition, natural thymocytotoxic autoantibody (NTA) titer in serum of SHR was also increased with aging and this increase was suppressed by feeding high VE diet until 12 weeks old after which it showed the same trend as that of SHR fed the control diet. These results suggest that VE induces the prevention in cellular immune functions decreased with aging in SHR, which is due to the increased production of IL2 and the decreased production of NTA from thymocytes following VE supplementation.