Identification of a novel type 1 diabetes-specific epitope by screening phage libraries with sera from pre-diabetic patients.

We used random peptide libraries displayed on phage to search for ligands to insulin dependent diabetes mellitus-related antibodies and were able to identify several candidate disease-related peptides. One of them, clone 92, showed a significant difference in the frequency of reactivity with the sera of patients and normal controls. Human immunoglobulins immunopurified on phage 92 specifically stained the islets on human pancreatic sections. When injected into rabbits, the selected peptide elicited antibodies that also stained human and rat pancreatic sections, with a pattern similar to that observed with immunoglobulins purified from the sera of patients. No reactivity was observed in other tissues. Our results indicate that the peptide identified in this work mimics a novel, diabetes-related self-antigen.