HLA-DQ8-restricted CD4+ T-cell clones obtained from a T1D pancreatic infiltrate have been shown to recognize an hPPI epitope located in the C-peptide (57) that covers hPPI61-76 and hPPI80-97 for which we found responses in YES-RIP-hB7.1 mice and HLA-DQ8 T1D patients. Here, CD4 is linked to type 1 diabetes mellitus.