Dietary effect of tocopherols and tocotrienols on the immune function of spleen and mesenteric lymph node lymphocytes in Brown Norway rats.

The immunoregulatory effects of dietary alpha-tocopherol (Toc) and tocotrienols (T-3) on humoral and cell-mediated immunity and cytokine productions were examined in Brown Norway rats. We found that the IgA and IgG productivity of spleen and mesenteric lymph node (MLN) lymphocytes was significantly enhanced in the rats fed on Toc or T-3, irrespective of concanavalin A (Con A) stimulation of the lymphocytes. On the contrary, the IgE productivity of lymphocytes from the rats fed on Toc or T-3 was less without Con A stimulation, but was greater in the presence of Con A, especially in the T-3 group. Toc or T-3 feeding significantly decreased the proportion of CD4+ T cells and the ratio of CD4+/CD8+ in both spleen and MLN lymphocytes of the rats fed on Toc or T-3. The interferon-gamma productivity of MLN lymphocytes was higher in the rats fed on Toc or T-3 than in those fed on a control diet in the presence of Con A, while that of spleen lymphocytes was lower in the rats fed on Toc or T-3. In addition, T-3 feeding decreased the productivity of tumor necrosis factor-alpha of spleen lymphocytes, while it enhanced the productivity of MLN lymphocytes. These results suggest that oral administration of Toc and T-3 affects the proliferation and function of spleen and MLN lymphocytes.

Effect of dietary fats and sesamin on the lipid metabolism and immune function of Sprague-Dawley rats.

We examined the effect of three dietary fats, safflower oil (SAF) rich in linoleic acid, borage oil (BOR) rich in gamma-linolenic acid, and perilla oil (PER) rich in alpha-linolenic acid, on the lipid metabolism, and chemical mediator and immunoglobulin levels in Sprague-Dawley rats, as well as the dietary effect of sesame-derived antioxidative sesamin. The serum cholesterol, phospholipid, triglyceride, prostaglandin E2 level and splenic leukotriene B4 level were lower in the rats fed on BOR or PER than in those fed on SAF. SES feeding suppressed the expression of the lipid-decreasing effect of BOR, but not in the rats fed on PER. In respect of the fatty acid composition of the liver and spleen, PER feeding gave a lower arachidonic acid level, and higher eicosapentaenoic and docosahexaenoic acid levels than SAF feeding did, while the effect of BOR feeding was marginal. The effect of SES feeding on fatty acid composition was much smaller than that of dietary fats. In respect of immunoglobulin production, PER + SES feeding gave the lowest IgE productivity in the mesenteric lymph node lymphocytes. These results suggest that PER feeding regulated lipid metabolism and exerted an anti-allergic effect by a different mechanism from that with BOR feeding.

Effects of sesamin and alpha-tocopherol, individually or in combination, on the polyunsaturated fatty acid metabolism, chemical mediator production, and immunoglobulin levels in Sprague-Dawley rats.

Feeding sesamin and alpha-tocopherol in combination, both at the 0.5% dietary level, to Sprague-Dawley rats for 3 weeks resulted in a trend toward decreasing the proportion of 20:4n-6 and 22:5n-6 and increasing that of 18:2n-6 in phosphatidylcholine from various tissues, suggesting interference with the metabolism of linoleic acid. This dietary manipulation significantly reduced the production of leukotriene C4 in the lung, the splenic production of leukotriene B4, and reduction of the plasma histamine level. Simultaneous administration of sesamin and alpha-tocopherol significantly increased the production of IgA, IgG, and IgM by mesenteric lymph node lymphocytes, while the IgE level tended to be reduced. These effects were not necessarily apparent by feeding these compounds separately. Thus, sesamin and alpha-tocopherol in combination would be effective for regulating the eicosanoid production and modifying the immune function.