Permanent effector phenotype of neuroantigen-specific T cells acquired in the central nervous system during experimental allergic encephalomyelitis.

Experimental autoimmune encephalomyelitis (EAE) is regarded as an animal model of the human autoimmune disease multiple sclerosis (MS). Autoreactive T cells are present in the peripheral T cell repertoire of healthy mice and mediate clinical autoimmune disease only after activation by immunization or pathogens and migrate into the central nervous system (CNS). Because it is not known whether autoreactive T cells are regulated differentially once entering the CNS we investigated cytokine regulation in T cells from peripheral lymphatic organs and from the inflamed CNS ex vivo obtained from SJL mice after inducing relapsing-remitting EAE with PLP peptide 139-151. We show here that during acute EAE, an interleukin-2 (IL-2) biased T cell response exists in the spleen, while an interferon-gamma (IFN-gamma) biased T cell response prevails in the CNS of mice with acute EAE. The IFN-gamma biased phenotype was stable with optimized costimulation and even after in vitro stimulation with IL-2. After adoptive transfer into naïve syngeneic mice these T cells were only partially reversed to an IL-2 biased phenotype. These findings of our work suggest that a permanent effector phenotype of neuroantigen-specific T cells is finally acquired in the CNS in EAE.