Retinal antigen–specific T cells that have not been eliminated in the thymus encounter an activating stimulus in the context of costimulatory “danger” signals, escape from the control of nTregs, and differentiate into pathogenic effector T cells. These undergo clonal expansion, migrate to the eye, break down the blood-retinal barrier, and recruit inflammatory leukocytes from the circulation. The resulting inflammation results in damage to the tissue and release of ocular antigens, which triggers eye-specific regulatory mechanisms that terminate the disease and limit pathology. mTECs, medullary thymic epithelial cells. Modified with permission from Immunological Reviews (24).