An Orally Supplemented Mononucleotide Mixture Prevents the Decrease in T Cell-Dependent Humoral Immunity in C57BL/6 Mice Fed a Nucleotide-Free Diet

Abstract

T cell-dependent humoral immune responses are lower in mice fed a nucleotide-free (NF) diet. In a previous study, a mononucleotide and nucleoside mixture prevented the decrease in humoral immune responses in mice fed a NF diet when a total of seven doses [2100 µmol/(kg·dose)] were administered intraperitoneally. In the present study, C57BL/6 (B6) mice were fed a NF diet for 3 wk with or without mononucleotide mixture (MM) supplementation. The MM was given at the levels of 14 or 70 µmol/(kg·d) by daily gavage feeding for 3 wk. Control mice were fed a NF diet without supplements (negative control) or a NF diet plus the mononucleotide/nucleoside mixture administered intraperitoneally (positive control). Both doses of MM prevented the decrease in T-dependent antibody (Ab) production in mice fed a NF diet as effectively as positive controls. T-helper (Th) spleen cells from mice of each diet group were enriched, mixed with Th cell-depleted spleen cells from each diet group, and antigen-primed in the culture. The number of Ab-secreting cells formed was higher with Th cells from mice with oral MM supplements or from positive controls than with those from mice without nucleotide supplement. The source of Th cell-depleted spleen cells did not influence the number of Ab-secreting cells. Thus, orally supplemented nucleotides can prevent the suppression of Th cell-dependent humoral immunity in mice fed a NF diet with doses likely to be provided by dietary sources.