Islet Amyloid Polypeptide Is a Target Antigen for Diabetogenic CD4+ T Cells

OBJECTIVE-To investigate autoantigens in beta-cells, we have used a panel of pathogenic T-cell clones that were derived from the NOD mouse. Our particular focus in this study was on the identification of the target antigen for the highly diabetogenic T-cell clone BDC-5.2.9. RESEARCH DESIGN AND METHODS-To purify beta-cell antigens, we applied sequential size exclusion chromatography and reverse-phase high-performance liquid chromatography to membrane preparations of beta-cell tumors. The presence of antigen was monitored by measuring the interferon-gamma production of BDC-5.2.9 in response to chromatographic fractions in the presence of NOD antigen-presenting cells. Peak antigenic fractions were analyzed by ion-trap mass spectrometry, and candidate proteins were further investigated through peptide analysis and, where possible, testing of islet tissue from gene knockout mice. RESULTS-Mass-spectrometric analysis revealed the presence of islet amyloid polypeptide (IAPP) in antigen-containing fractions. Confirmation of IAPP as the antigen target was demonstrated by the inability of islets from IAPP-deficient mice to stimulate BDC-5.2.9 in vitro and in vivo and by the existence of an IAPP-derived peptide that strongly stimulates BCD-5.2.9. CONCLUSIONS-IAPP is the target antigen for the diabetogenic CD4 T-cell clone BDC-5.2.9. Diabetes 60:2325-2330, 2011