Effect of Dietary Level of Pectin on Immunoglobulin and Cytokine Production by Mesenteric Lymph Node Lymphocytes and Interleukin-2 Receptor in Rats.

Abstract

The present study was carried out to clarify the dietary effect of pectin on imunoglobulin (Ig) and cytokine production of rat lymphocytes. Rats were fed a diet containing 0 (cellulose) and 1, 2 or 5% levels of pectin for 2 weeks. Dietary pectin, as compared with cellulose, enhanced production of IgA, IgG and IgM by mesenteric lymph node lymphocytes, while reducing IgE production. In the lymphocytes obtained from the rats fed pectin, interferon-␥ production and interleukin-2 receptor expression were significantly higher than in those from the rats fed cellulose. These results suggest that the effect of dietary pectin was exerted through the functioning of Th 1 cells. In this context, dietary pectin was expected to alleviate the type 1 allergy reaction.Keywords: dietary pectin, interferon-␥, interleukin-2 , IgE production, mesenteric lymph node There is an increasing interest in both physiological and pharmacological effects of dietary fibers (Brydon, 1995, Lupton, 1995, Jacobs, 1988. Pectin is one form of dietary fiber attracting particular attention, as it consistently exerts a hypocholesterolemic effect (Truswell, 1977). It is possible that dietary fibers also influence immune function as a consequence of changes in mucosal structure and gut microflora. We previously reported (Lim et al., 1997) that dietary pectin may influence the immune function of intestine in rat. To confirm and expand this observation, we examined here the dose-dependent effect of dietary pectin on immune parameters of rats. Since dietary pectin exerts its effects entirely, but not exclusively, in the gut, we focused this study on the response of mesenteric lymph node (MLN) lymphocytes in rats, by measuring the effect of dietary pectin on Ig and cytokine production in relation to cellulose. The response of some cytokines was also measured.Enzyme-linked immunosorbent kits for TNF-␣ and IFN-␥ were purchased from Biosource International Co. (Camarillo, CA). The ELISA methods for measurement of Igs were described elsewhere (Engvall & Perlman, 1971). Four week old male Sprague-Dawley rats were obtained from Seiwa Experimental Animals (Fukuoka) and housed individually in a room with controlled temperature and light of 20-23˚C and a light cycle of 08:00 to 20:00. After acclimatization for 7 days, rats were divided into 4 groups of 6 each and allowed free access to one of the experimental diets and deionized water. The experimental diets were prepared according to the recommendation of the American Institute of Nutrition (AIN 93G diet) (Reeves et al., 1993). Highly methoxylated edible pectin (esterification ratio of 65-73%) with a purity of more than 95% was a gift from Snow Brand Co. Tokyo, and added to the diet at the 0, 1, 2 or 5% level in place of cellulose. After 2 weeks of feeding rats were killed under diethyl ether anesthesia. MLN was excised and the lymphocytes were harvested (Lim et al., 1994).This experiment was carried out under the control of the guidelines for Animal Experiments in the Faculty of Agriculture and the Graduate Course ...

Effect of Dietary Pectin on the Production of Immunoglobulins and Cytokines by Mesenteric Lymph Node Lymphocytes in Mouse Colitis Induced with Dextran Sulfate Sodium

“…The enzyme-linked immunosorbent assay (ELISA) for mice IgE and IgA used 0.05z Tween 20 in PBS (TPBS) for rinsing and Block Ace (Dainihon Pharmaceutical Co., Osaka, Japan) for blocking and dilution of the antibodies as described previously. 4,15,21,22) All other reagent-grade chemicals were purchased from Sigma (St. Louis, MO, U.S.A.).…”

“…The lymphocytes were cultured in 10z fetal bovine serum (FBS; Invitrogen Corporation, Grand Island, NY, U.S.A) W RPMI 1640 medium, and the IgE and IgA contents of the culture supernatant were measured by ELISA. 4,14,15,21,22) The cell viability was measured by trypan blue staining, the viability by this preparation being more than 95z of the total cells.…”

“…14,17) Our previous results have shown that the eŠect of dietary pectin was exerted through Th1 cells. 14,15) IFN-g production and IL-2 receptor expression are both increased with dietary pectin in the MLN. 14,15) Th1 cytokines as IFN-g and IL-2 can oppose the Th2 function and W or its development, and thereby inhibit the production of IL-4 and IL-10.…”

“…14,15) IFN-g production and IL-2 receptor expression are both increased with dietary pectin in the MLN. 14,15) Th1 cytokines as IFN-g and IL-2 can oppose the Th2 function and W or its development, and thereby inhibit the production of IL-4 and IL-10. In addition, dietary pectin inhibits the synthesis of the pro-in‰amma-tory cytokine, TNF-a.…”

“…12,13) We have previously reported that water-soluble dietaryˆber might have an immunoregulatory function in the intestinal immune system. [14][15][16] In addition, dietary pectin might regulate immunoglobulin (Ig) production by mesenteric lymph node (MLN) lymphocytes, and it was suggested that pectin exerted anti-allergic activity. 14,17) Our previous results have shown that the eŠect of dietary pectin was exerted through Th1 cells.…”