Subsets of CD4+ and CD8+ T cells are thought to have either pathogenic (e.g. CD4+ Th17 cell lines) or protective (e.g. CD8+ Treg) roles, or in some cases both (Cd4+ γδT cells).12 Animal models of uveitis, particularly experimental autoimmune uveitis (EAU) in which a susceptible animal is immunized with retinal derived proteins, have provided valuable information on disease pathogenesis. The gene discussed is CD4; the disease is uveitis.