Priming of Autoreactive Cells Is Inhibited by Immunogenic Peptides Which Are Competitive for Major Histocompatibility Complex Class I Binding

In the present study, we investigated if priming of autoreactive $CD8^+T$ cells would be inhibited by competitive peptides for major histocompatibility complex (MHC) class I binding. We used a mouse model of vitiligo which is induced by immunization of $K^b$-binding tyrosinase-related protein 2 (TRP2)-180 peptide. Competitive peptides for $K^b$ binding inhibited IFN-${\gamma}$production and proliferation of TRP2-180-specific $CD8^+T$ cells upon ex vivo peptide restimulation, while other MHC class I-binding peptides did not. In mice, the capability of inhibition was influenced by T-cell immunogenicity of the competitive peptides. The competitive peptide with a high T-cell immunogenicity efficiently inhibited priming of TRP2-180-specific $CD8^+T$ cells in vivo, whereas the competitive peptide with a low T-cell immunogenicity did not. Taken together, the inhibition of priming of autoreactive $CD8^+T$ cells depends on not only competition of peptides for MHC class I binding but also competitive peptide-specific $CD8^+T$ cells, suggesting that clonal expansion of autoreactive T cells would be affected by expansion of competitive peptide-specific T cells. This result provides new insights into the development of competitive peptides-based therapy for the treatment of autoimmune diseases.