Dietary fatty acid modulates actions of nucleotides on humoral immune responses

Polynucleotides enhance T cell-dependent antibody production in culture. Impaired antibody production in mice fed a nucleotide-free diet can be easily restored by in vivo supplementation of both a mononucleotide-nucleoside mixture (OG-VI) and polynucleotides. Polynucleotides appear to act partly by modulating antigen presentation processes mediated by cell surface molecules. We examined whether dietary fatty acid manipulation alters nucleotides' actions on humoral immunity. Antibody production was studied in C57B1/6 mice fed 1) a nucleotide-free diet high in saturated fatty acid (SFA diet), 2) a nucleotide-free diet high in polyunsaturated fatty acid (PUFA diet), and 3) a regular nucleotide-free diet (control). In vivo and in vitro T cell- dependent antibody production decreased in all groups, but mice fed the SFA diet produced more antibody in vivo than did mice in the other diet groups. Spleen cells from mice fed the SFA diet also produced more interferon-α when stimulated with mitogens than did those from mice fed the control diet. In contrast, polynucleotides enhanced in vitro antibody production much less efficiently in mice fed the SFA diet than in the other mice and in vivo supplementation of OG-VI was also less effective in restoring impaired antibody production in these mice. A diet with a high content of SFA may alter nucleotides' action on humoral immune responses, in addition to its direct effects on immune functions.