Selective delivery of β cell antigen to dendritic cells in vivo leads to deletion and tolerance of autoreactive CD8⁺ T cells in NOD mice

Type 1 diabetes (T1D) is an autoimmune disease resulting from defects in central and peripheral tolerance and characterized by T cell-mediated destruction of islet β cells. Cytotoxic CD8⁺ T cells, reactive to β cell antigens, are required for T1D development in the NOD mouse model of the disease, and CD8⁺ T cells specific for β cell antigens can be detected in the peripheral blood of T1D patients. It has been evident that in nonautoimmune-prone mice, dendritic cells (DCs) present model antigens in a tolerogenic manner in the steady state, e.g., in the absence of infection, and cause T cells to proliferate initially but then to be deleted or rendered unresponsive. However, this fundamental concept has not been evaluated in the setting of a spontaneous autoimmune disease. To do so, we delivered a mimotope peptide, recognized by the diabetogenic CD8⁺ T cell clone AI4, to DCs in NOD mice via the endocytic receptor DEC-205. Proliferation of transferred antigen-specific T cells was initially observed, but this was followed by deletion. Tolerance was achieved because rechallenge of mice with the mimotope peptide in adjuvant did not induce an immune response. Thus, targeting of DCs with β cell antigens leads to deletion of autoreactive CD8⁺ T cells even in the context of ongoing autoimmunity in NOD mice with known tolerance defects. Our results provide support for the development of DC targeting of self antigens for treatment of chronic T cell-mediated autoimmune diseases.