n −3 PUFA fail to affect in vivo , antigen-driven CD8 + T-cell proliferation in the spleen of naïve mice

Abstract

One of the most frequently reported immunomodulatory actions of n −3 PUFA is their ability to diminish in vivo lymphocyte proliferation. The purpose of this study was to determine if n −3 PUFA intake affects the kinetics or magnitude of the antigen-driven expansion of CD8 + T-lymphocytes in vivo . In this study we utilized a well-characterized model of T-cell immunity (i.e. infection with the intracellular bacterium, Listeria monocytogenes ). Weanling BALB/c mice were fed one of two experimental diets that differed solely in fat source. Our control diet contained lard (180g/kg) and was devoid of long-chain n −3 PUFA. The experimental diet contained 150g/kg menhaden fish oil and 30g/kg corn oil, thus providing approximately 8% of energy from long-chain n −3 PUFA. After 4 weeks, mice were infected intravenously with 10 6 colony-forming units of actA-deficient L. monocytogenes . Clonal expansion of antigen-specific CD8 + T-cells in the spleen was measured at 5, 7, 9 and 14d post-challenge using a class I MHC tetramer loaded with the immunodominant peptide from this pathogen (i.e. K d :LLO 91–99 ). We report that feeding mice a diet rich in n −3 fatty acids did not significantly impact either the kinetics or magnitude of in vivo , antigen-driven expansion of CD8 + T-cells. Furthermore, contraction of this T-cell population was not affected by n −3 PUFA treatment. To our knowledge this is the first time MHC tetramers have been used to investigate the influence of n −3 PUFA on in vivo CD8 + T-cell proliferation.