MODULATION OF MACROPHAGE CYTOKINE PRODUCTION BY CONJUGATED LINOLEIC ACIDS IS INFLUENCED BY THE DIETARY N-6-N-3 FATTY-ACID RATIO

Conjugated linoleic acids (CLA) are a mixture of 18:2 isometric fatty acids that have conjugated double bonds. We undertook this study to de termine if CLA altered spleen fatty acid composition, macrophage cytok ine production, and liver prostaglandin E-2 (PGE(2)) biosynthesis in t he presence of varying ratios of (n-6) and (n-3) polyunsaturated fatty acids (PUFA). Groups of six rats were fed diets (AIN-93G) containing soybean oil (SBO) or menhaden oil and safflower oil (MSO), with CLA (1 0 mu g/kg) or without CLA. Spleens of rats consuming CLA contained the t9,c11 and t10,c12 isomers of CLA and a lower content of 18:1 fatty a cids. CLA significantly reduced basal and lipopolysaccharide (LPS) ind uced levels of interleukin-6 (IL-6) by resident peritoneal macrophages in rats given SBO. CLA also reduced basal levels of tumor necrosis fa ctor (TNF) production in both diets, but had no effect on LPS-induced levels of TNF. CLA had no effect on IL-1 production, but macrophage IL -1 production was increased in MSO fed rats compared with SBO fed rats . Rats given MSO had reduced PGE(2) production in spleen compared with SBO fed rats. In SBO fed rats, CLA caused some reduction in PGE(2), b ut the effect was not significant. The effect of CLA on PGE(2) product ion may be dependent on the type of dietary fat consumed and the organ being studied. (C) Elsevier Science Inc. 1998.