Immunologically ignorant autoreactive T cells, epitope spreading and repertoire limitation.

The factors that may cause antigen-presenting cells to alter the pattern of protein processing and presentation to autoreactive T cells, and thereby stimulate autoimmune disease, are currently under debate. In this article, Chris Elson and colleagues suggest that cytokines associated with T helper 1 (Th1) cells alter the processing of proteins and that this effect can be counteracted by Th2-associated cytokines.