Dietary supplementation with conjugated linoleic acid increased its concentration in human peripheral blood mononuclear cells, but did not alter their function

The purpose of this study was to examine if conjugated linoleic acid (CLA) supplementation of diets would alter fatty acid (FA) composition and functi on of peripheral blood mononuclear cells (PBMC). Seventeen women, 20-41 yr, participated in a 93-d study conducted at the Metabolic Research Unit. The same diet (19, 30, and 51% energy from protein, fat, and carbohydrate, res pectively) was fed to all subjects throughout the study. Seven subjects (co ntrol group) supplemented their diet with six daily capsules (1 g each) of placebo oil (sunflower) for 93 d. For the other 10 subjects (CLA group), th e supplement was changed to an equivalent amount of Tonalin capsules for th e last 63 d of the study. Tonalin provided 3.9 g/d of a mixture of CLA isom ers (trans-10,cis-12, 22.6%; cis-11,trans-13, 23.6%; cis-9,trans-11, 17.6%; trans-8,cis-10, 16.6%,; other isomers 19.6%), and 2.1 g/d of other FA. PBM C isolated on study days 30 and 90 were used to assess intracellular cytoki nes by flow cytometry, secreted cytokines, and eicosanoid by enzyme-linked immonosorbent assay, and FA composition by gas-liquid chromatography. After supplementation, total CLA concentration increased from 0.012 to, 0.97% (P < 0.0001) in PBMC lipids, but it did not significantly alter the concentra tion of other FA. CLA supplementation did not alter the in vitro secretion of prostaglandin E-2, leukotriene B-4, interleukin-1 beta (IL-1 beta), or t umor necrosis factor a (TNF alpha) by PBMC simulated with lipopolysaccharid e, and the secretion of IL-2 by PBMC stimulated with phytohemagglutinin. No r did it alter the percentage T cells producing IL-2, interferon gamma, and percentage of monocytes producing TNF alpha. The intracellular concentrati on of these cytokines was also not altered. None of the variables tested ch anged in the control group. Our results show that CLA supplementation incre ased its concentration in PBMC lipids, but did not alter their functions.