Antigens targeted by prevalent pathogennic T cells in type 1 diabetes and uses thereof

The present invention is based on the identification of a predominant ligand of CD8 + T cells that are responsible for type 1 diabetes. That ligand is islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP). Several CD8 + T cell-binding peptides from IGRP are identified, including the peptide comprising amino acids 206-214 of the IGRP sequence, which has high avidity to the most prevalent T cell receptor of pathogenic CD8 + T cells in autoimmune diabetes. The invention thus provides oligopeptide and polypeptide compositions comprising YLKTN(A/I/L/V)FL (SEQ ID NO:3), FLWSVFWLI (SEQ ID NO:4), (T/A)YY(G/T)FLNFM (SEQ ID NO:5), LR(L/V)(F/L)(G/N)IDLL (SEQ ID NO:6), KWCANPDWI (SEQ ID NO:7), and SFCKSASIP (SEQ ID NO:8). Also provided are oligopeptide compositions 8-10 amino acids in length and completely homologous with a mammalian IGRP, where the oligopeptide is capable of binding a human MHC class I molecule. Additionally, various methods of treating a mammal using the above compositions are provided, where the mammal is at risk for or has type 1 diabetes. Also provided are methods of preventing a CD8 + T cell that is cytotoxic to pancreatic islet β-cells from destroying a mammalian β-cell, where the methods also use the above compositions. Further provided are methods for determining whether a mammal is at risk for or has type 1 diabetes, where the methods use the above compositions.