Further experiments using FoxP3+CD25hiCD4+ Treg isolated from > P50 3A9 mice (naïve) or from > P50 dTg (AgX), showed that 3A9 Treg were ineffective while AgX Treg, not only halted disease progression but reversed the pathological changes (retinal vasculitis) in some cases. The gene discussed is FOXP3; the disease is retinal vasculitis.