Figure 3.

T-bet is not required for Treg cell suppressive function. Varied numbers of Tg4.WT or Tg4.T-bet^-/- nTreg (A) or iTreg (B) were co-cultured with a fixed number of naïve Tg4 responder cells and stimulated with MBP Ac1-9 (as described in Section “Materials and Methods”). Data are from one of two experiments giving consistent results. (C–F) C57BL/6xB10.PL were immunized with MBP Ac1-9 1 day after transfer of 1 × 10⁶ naïve CD4⁺ Tg4 responder cells (CD90.1), with or without 1 × 10⁶ Tg4.WT or Tg4.T-bet^-/- iTreg (CD45.1) for development of EAE (C) (mean clinical scores ± SEM), or for ex vivo analysis of spleen and dLN after 7 days (D–F). Ex vivo numbers of Tg4.CD90.1 responder cells (D), Ki-67⁺ responder cells (E). IFN-γ⁺ responder cells after overnight culture with MBP peptide (F). Data are from one of three experiments giving consistent results, n = 5 mice per group. (G) IFN-γ production by Tg4 Th1 responder cells co-cultured with Tg4.WT or Tg4.T-bet^-/- iTreg cells. Data are from one of two experiments giving consistent results.