The TLR-specific adjuvants R-848 and CpG-B endorse the immunological reaction of neonatal antigen-presenting cells

Background: Preterm neonates display an impaired vaccine response. Neonatal antigen-presenting cells (APCs) are less effective to induce an adaptive immune response and to promote the development of immunological memory. Efficient adjuvantal toll-like receptor (TLR)-triggering may overcome the neonatal immunological impairment. Accordingly, the aim of this study was to investigate the immunostimulatory action of R-848 and CpG-B on neonatal APCs. Methods: Surface marker and cytokine secretion of APCs were evaluated after incubation of cord blood and peripheral blood mononuclear cells with the indicated adjuvants and were analyzed using flow cytometry. Results: TLR-specific stimulation resulted in a significant induction of costimulatory molecules on neonatal APCs. Stimulation with R-848 resulted in significant higher secretion of TNF alpha, IL-6, IL-10, IL-12/IL-23p40, IL-12p70, and IFN-gamma. Interestingly, CpG-B resulted in significant higher secretion of TNFa and IL-6. Conclusion: In summary, the incubation of TLR-agonists induced activation and maturation of neonatal APCs. These data show that modern TLR-specific adjuvants achieve a direct effect and potent upregulation of activation and maturation markers and cytokines in preterm neonates. We thus conclude that agents triggering TLRs might possibly overcome neonatal lack of vaccine responses.