Essential role of CD8⁺CD122⁺ regulatory T cells in the recovery from experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is one of the best-documented animal models of autoimmune disease. We examined the role of CD8⁺CD122⁺ regulatory T cells, which we previously identified as naturally occurring regulatory T cells that effectively regulate CD8⁺ T cells, in EAE. Depletion of CD8⁺CD122⁺ regulatory T cells by in vivo administration of anti-CD122 mAb resulted in persistent EAE symptoms. Transfer of CD8⁺CD122⁺ regulatory T cells into EAE mice at the peak EAE score clearly improved symptoms, indicating an important role of CD8⁺CD122⁺ regulatory T cells in the recovery phase of EAE. This was further confirmed by an increase and a decrease in the number of infiltrating T cells in the CNS and T cell cytokine production in mice that were depleted of or complemented with CD8 ⁺CD122⁺ cells. Furthermore, transfer of preactivated CD8⁺CD122⁺ regulatory T cells resulted in diminished EAE symptoms, especially in the recovery phase of EAE. These results elucidate the essential role of CD8⁺CD122⁺ regulatory T cells in the recovery phase of EAE and suggest the preventive effect of preactivated CD8 ⁺CD122⁺ regulatory T cells for EAE.