Nucleotide actions on humoral immune responses.

Previous studies indicate the importance of dietary nucleotides in maintaining optimal cellular immunity. Our studies using murine spleen cells showed that polynucleotides significantly increase in vitro antibody production in response to T-cell-dependent antigen. They seem to exert actions on T-helper cells at antigen presentation, perhaps during cognitive cell-cell interactions. They do not augment the actions of cloned, antigen-specific, activated T-helper cells, nor do they increase antibody production in response to T-cell-independent antigen or polyclonal B-cell activation. Polynucleotides increase in vitro human immunoglobulin production in response to T-cell-dependent stimuli and antigen. Humoral immune responses to T-cell-dependent antigen were depressed in mice fed a nucleotide-free diet, but were restored by a mononucleotide-nucleoside mixture. Responses to T-cell-independent antigen remained intact in these mice. The mononucleotide-nucleoside mixture had no effect on in vitro antibody production and did not further increase humoral immune responses in mice fed regular lab chow. These results suggest that the in vivo actions of polynucleotides on humoral immune responses may reflect local immune responses, perhaps at the site of inflammation. Mononucleotides and nucleosides may be incorporated into the tissue nucleotide pool fairly rapidly in a state of relative nucleotide deficiency and help restore T-cell-dependent humoral immune responses. Our findings may further support the importance of dietary nucleotides.