IFN-?– and IL-10–expressing virus epitope-specific Foxp3(+) T reg cells in the central nervous system during encephalomyelitis

Zhao, Jingxian; Zhao, Jincun; Fett, Craig; Trandem, Kathryn; Fleming, Erica; Perlman, Stanley

To further characterize these virus-specific T reg cells, we next assessed whether they produced cytokines in response to peptide stimulation. Remarkably, 4-6% of all CNS (pooled brain and spinal cord)-derived T reg cells expressed IFN-, after peptide M133 stimulation at 14 d after infection (Fig. 2 A) . We also identified IFN- + T reg cells specific for a second rJ2.2-specific CD4 T cell epitope, S358 in the CNS. In experiments described later in this paper, cells were stimulated with M133 and S358 peptides together (M133 + S358) because virus-specific T reg cells were present in low numbers in the infected CNS (Fig. 2 B) . Virus-specific IFN- + T reg cells were detected as early as 6 d after infection, at the same Br ief Definitive Repor t fivefold, respectively, after in vivo BFA treatment, confirming in situ IFN- expression by T reg cells. Consistent with the in vitro peptide stimulation analyses, the mean fluorescence intensity of IFN- expression was lower in T reg cells compared with effector CD4 T cells after in vivo BFA treatment (Fig. 2 F) .