Abstract:Objective: To investigate the immunoregulatory effect of tolerogenic dendritic cells (tolDCs) loaded with hybrid insulin peptides (HIPs) on diabetogenic BDC2.5 T cells. METHODS: Bone marrow derived imature DCs(iDCs)of Non-obese Diabetic(NOD)mice were induced with cytokines,and additional vitamin D3 was added to generate tolDCs. After 24h stimulation with lipopolysaccharide (LPS), The supernatant of LPS-iDCs and LPS-tolDCs was collected to detect cytokines IL-12p70 and TGF-β, and the phenotype of the above DCs was identified by morphology and flow cytometry. Diabetogenic T cells, namely BDC2.5 CD4+ T cells were incubated with HIPs-loaded DCs for 3 days, and the proliferation, activation and Tregs production were detected. RESULTS: Phenotypic identification results showed that tolDCs had low expression of costimulatory molecules CD80、CD86 and high expression of coinhibitory molecule PD-L1.The phenotype of tolDCs remained stable under the stimulation of LPS, and the secretion of IL-12p70 was decreased while the secretion of TGF-β was increased compared with LPS-iDCs. Both tolDCs and LPS-tolDCs loaded with HIPs could inhibit the proliferation and activation of BDC2.5 T cells and induce the production of antigen-specific regulatory T cells(Tregs). Conclusion: HIPs loaded tolerogenic dendritic cells can inhibit the proliferation and activation of diabetogenic BDC2.5 T cells and promote the production of Tregs through their stable tolerance phenotype and function.