Effects of dietary docosahexaenoic acid on surface molecules involved in Tcell proliferation

It is known that n-3 polyunsaturated fatty acids (PUFA) such as docosahexae noic acid (DHA) suppress immunity as compared with n-6 PUFA such as linolei c acid (LA), but the mechanism involved in this phenomenon is still unclear . The present study was designed to assess the effect of dietary DHA on the surface molecules involved in T cell proliferation. Weanling male C57BL/6 mice were divided into four dietary groups that were fed a 10% fat diet for 4 weeks varying in amounts of DHA and LA. As the dietary DHA concentration increased, the surface expression of CD4 and CD8 on splenic T cells decrea sed, while that of CD28 increased. The surface expression of CD3, however, was invariable in all dietary groups. DNA synthesis of splenic T cells, ind uced by CD3 crosslinkage with anti-CD3E monoclonal antibody in the presence of CD28-mediated costimulation, increased as the DHA concentration was ele vated. These observations suggest that diets rich in DHA erect some of thei r immunomodulatory effects by a downregulation of surface expression of CD4 and CD8 and by an upregulation of CD28-mediated costimulatory signal. (C) 1999 Elsevier Science B.V. All rights reserved.