Dietary conjugated linoleic acid increases immunoglobulin productivity of Sprague-Dawley rat spleen lymphocytes

The dietary effects of conjugated linoleic acid (CLA) on Ig production of S prague-Dawley rats were examined at various doses such as 0 (control), 0.05 , 0.10, 0.25, and 0.50%. CLA increased IgG and IgM production of spleen lym phocytes in a dose-dependent manner, and these levels reached a plateau at 0.25%, IgA production was not detected in the control group, while it was d etected in all CLA-fed groups and IgA productivity of spleen lymphocytes in creased in a dose-dependent manner at the doses from 0.05 to 0.50%, Dietary CLA did not affect serum Ig levels. The major fatty acid composition of sp leen lymphocytes was not affected by dietary CLA, which itself was hardly i ncorporated into the cells, In an in vitro assay, the effects of CLA and it s oxidative derivatives, furan type fatty acids, on Ig productivity were al so examined. As a result, 100 muM CLA suppressed Ig production of spleen ly mphocytes and the degree was as follows IgA>IgG>IgM. Each CLA isomer and th e furan type fatty acids also suppressed Ig production but the degree was w eaker than the mixture of CLA isomers. In this result, dietary CLA increase d Ig productivity of spleen lymphocytes in vivo.