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

For M133 TCR Rg mice, to identify M133-specific T cell receptors, splenocytes were harvested 7 d after infection from mice infected i.p. with the neurovirulent JHM strain of mouse hepatitis virus and were stimulated with 5 µM of peptide M133. After stimulation, epitope-specific CD4 T cells useful for detecting epitope-specific T reg cells because IL-10 was produced in virally infected mice and in mice with EAE after peptide stimulation ( Fig. 3 and Fig. S5 ). IFN- production by T reg cells was previously demonstrated in a lethal toxoplasmosis infection (Oldenhove et al., 2009 ), but our results indicate that IFN- is also expressed in the context of a nonlethal viral infection and continues even as the inflammatory response subsides (Fig. 2) . The continued expression of IFN- by virus-specific T reg cells likely occurs because virus antigen persists in the infected CNS (Bergmann et al., 2006; Zhao et al., 2009) . Epitope M133-specific T reg cells suppressed proliferation of effector CD4 T cells responding to the same epitope, suggesting that if IFN- expression diminishes T reg cell suppressive function, its effect is limited. rJ2.2specific T reg cells were detected in the CNS and not draining CLNs or spleen ( Fig. 1 and not depicted) , suggesting that they function by directly inhibiting T cell function or diminishing antigen presentation by microglia or other antigen-presenting cells at the site of inflammation.