PDCD1 and myocarditis: Our results further suggest that tissue derived antigen cross-priming of dendritic cells is required for expansion of self-reactive effector CD8+ T cells, and that loss of suppression of self-reactive effector CD8+ T cell clones by PD-1−/−dendritic cells is responsible, at least in part, for expansion of self-reactive CD8+ T cell clones and the development of sustained low-grade myocarditis in the ISO-injured PD1−/−mice.