The present invention is based on the identification of a predominant ligand of CD8+ T cells that are responsible eq 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, FLWSVFWLI, (T / A)YY / G / T)FLNFM, LR(LV)(F / L)(G / N)IDLL, KWCANPDWI, and SFCKSASIP. 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.