Regulatory T-cells have a prominent role in the immune modulated vaccine response by specific oligosaccharides

Regulatory T-cells are increasingly important in vaccine strategies. In a Flu-vaccination model the role of CD4+CD25+Foxp3+ regulatory T-cells (Tregs) and the immune modulation by orally supplied prebiotic oligosaccharides consisting of scGOS/lcFOS/pAOS, were assessed using anti-CD25 (PC61) mediated depletion studies. As expected, in C57BL/6J mice the Flu-vaccination resulted in significantly (p < 0.001) increased DTH responses when receiving scGOS/lcFOS/pAOS. In addition, increased T-bet expression of activated CD4+ T-cells was detected compared to placebo. In vivo depletion of CD25+ Tregs significantly (p < 0.05) increased basal DTH responses, indicating the suppressive function of these CD25+ Tregs normally present. Surprisingly, in vivo Tregs depletion diminished scGOS/lcFOS/pAOS induced immune modulation completely to control levels (p < 0.05). Although no difference in number, percentage or activation of Tregs could be determined after scGOS/lcFOS/pAOS supplementation, changes in Treg function still remains to be investigated. In conclusion, CD25+ Tregs have an important role in modulated Flu-vaccine responses induced by scGOS/lcFOS/pAOS.