HLA-C and type 1 diabetes mellitus: A number of antigen-specific immunotherapies aiming to modulate T1D-associated T cells, i.e., nanoparticle vaccination, small molecules or monoclonal antibodies to block formation of the tri-molecular complex, and infusion of antigen-specific regulatory T cells, require precise molecular information about peptide-MHC complexes targeted by T cells (12–19).