Studies on the Possible Regulatory Function of Dietary Alpha-Linolenic Acid in Prostaglandin Synthesis by Immunocompetent Cells

126 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.Alpha-linolenate (18:3(omega)3) and its elongated, desaturated metabolites are known to predominate in certain tissues. The role of essential fatty acid (EFA), and therefore of PGs, in cell-mediated immunity has increasingly become of interest. Prostaglandins have been implicated in many areas of the immune response. Three studies were conducted examining both in vivo and in vitro rat immune models to study the regulatory influence of 18:3(omega)3 in activities where PGs play a significant role. The first study demonstrated that feeding a 10% fat diet containing a 1:1 ratio of 18:3(omega)3 to linoleate (18:2(omega)6) significantly depressed spleen and thymus PG(,1+2) synthesizing capacities in the immunochallenged rat. A more severe experimental allergic encephalomyelitis clinical score was also observed by rats fed the high (alpha)-linolenate diet.In the second study, the effect of different levels of dietary 18:3(omega)3 fed for varying lengths of time were examined. Extensive dietary 18:3(omega)3 incorporation of (omega)3 series fatty acid was accomplished in 4 months and by feeding through two generations using diets consisting of 18:3(omega)3 to 18:2(omega)6 ratios of either 1/1 or 3/1. Incorporation was characterized by a depression of (omega)6 fatty acids and increased incorporation of (omega)3 fatty acids. It is apparent that dietary (alpha)-linolenate significantly influences (omega)6 fatty acid derivative incorporation into tissues. Moreover, these changes correlated with marked decreases in the PG 1 and 2 synthesizing capacities of the examined tissues and they were found to be tissue specific.A third investigation revealed that when rats were fed the high 18:3(omega)3 diet, both splenocytes and peripheral lymphocytes (PL) (omega)6 fatty acids were shown to decrease in response to the reciprocal incorporation of (omega)3 fatty acid derivatives. The PG(,1+2(alpha)) synthesis over a 48 hour period by PHA-stimulated PL was shown to decrease with 18:3(omega)3 feeding. Despite these changes, the T cell in vitro blastogenic response to PHA was not altered in rats fed the high 18:3(omega)3 diet. These findings indicate that dietary 18:3(omega)3 may be used to modulate immune functions in which PGs play a significant role.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD