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

Identification of T reg cell-specific target epitopes in infected nontransgenic animals has proven difficult. Our results demonstrate the presence of virus-specific Foxp3 + T reg cells in the rJ2.2-infected CNS but also show that they are present at a low frequency (Figs. 1 and 2) . Detection was initially facilitated by the availability of M133-specific MHC class II tetramers. However, we previously showed that this tetramer was not as efficient as cytokine expression in identifying M133-specific effector CD4 T cells (Zhao et al., 2009) . Subsequently, we identified a greater frequency of M133-specific T reg cells by cytokine staining for IL-10 and IFN- after peptide stimulation. IL-10 expression may be particularly from the brains of rJ2.2-infected Foxp3 gfp mice at day 7 after infection and used them in direct ex vivo suppression assays. As a control, we isolated GFP + T reg cells from mice infected with rJ2.2.M Y135Q , which does not express epitope M133. As shown in Fig. 4 A, T reg cells harvested from rJ2.2, but not from rJ2.2.M Y135Q -infected mice, suppressed proliferation of brain-derived effector T cells after M133 peptide stimulation. In contrast, T reg cells from brains infected with either virus were suppressive after stimulation with anti-CD3 (Fig. 4 B) .