Recent observations in a virus-based diabetes models of the mouse [17, 71, 72] have taught us that beta-cell-antigen-specific T cells can recruit a high number of non-beta-cell-antigen-specific bystander T cells that add to the destruction of beta cells (more than 98% of infiltrating CD8 cells in the rat insulin promoter–lymphocytic choriomeningitis virus (RIP-LCMV) model are not viral-antigen-specific [17]). The gene discussed is CD8A; the disease is diabetes mellitus.