CD4 T cells and their antigens in the pathogenesis of autoimmune diabetes.

Pathogenesis of type 1 diabetes (T1D) is mediated by effector T cells and CD4 Th1 and Th17T cells have important roles in this process. While effector function of Th1 cells is well established, because of their inherent plasticity Th17 cells have been more controversial. Th17 cells contribute to pathogenicity, but several studies indicate that Th17 cells transfer disease through conversion to Th1 cells in vivo. CD4T cells are attracted to islets by β-cell antigens which include insulin and the two new autoantigens, chromogranin A and islet amyloid polypeptide, all proteins of the secretory granule. Peptides of insulin and ChgA bind to the NOD class II molecule in an unconventional manner and since autoantigenic peptides may typically bind to MHC with low affinity, it is postulated that post-translational modifications of β-cell peptides could contribute to the interaction between peptides, MHC, and the autoreactive TCR.