Fig. 2. Type-1 IFN is required for blockade of pT_reg conversion but not for induction of T_H1 immunity to dietary antigen.

(A) WT and IFNAR^−/− mice were inoculated perorally with 10⁸ PFU of T1L (n = 6 mice), 10⁸ PFU of T3D-RV (n = 6 mice), or PBS (sham, n = 6 mice) for 2 days. Mx1 expression in the mLN was analyzed by means of reverse transcription polymerase chain reaction (RT-PCR). (B and C) OT-II⁺ CD45.1⁺ CD4⁺ T cells were transferred into WT CD45.2⁺ or IFNAR^−/− CD45.2⁺ mice. One day after transfer, mice were inoculated perorally with 10⁸ PFU of T1L (n = 6 mice) or PBS (sham, n = 4 or 5 mice) and fed 1.5% OVA in the drinking water for 2 days. The expression of IL-12p40 on gated MHC-II⁺ CD11c⁺ CD103⁺ CD11b⁻ CD8α⁺ mLN DCs (B) and T-bet in OT-II⁺ CD45.1⁺ CD4⁺ T cells (C) in the mLN was evaluated by means of flow cytometry. (D to G) OT-II⁺ CD45.1⁺ CD4⁺ T cells were transferred into WT CD45.2⁺ or IFNAR^−/− CD45.2⁺ mice. One day after transfer, mice were inoculated with PBS (n = 7 mice) or 50 mg of poly(I:C) (n = 7 mice) intraperitoneally or 10¹⁰ PFU of T1L (n = 5 mice) perorally and fed an OVA-containing diet for 6 days. The intracellular expression of Foxp3 and IFN-γ in OT-II⁺ CD45.1⁺ CD4⁺ T cells in the mLN was evaluated by means of flow cytometry. Percentages and absolute numbers of Foxp3 [(D) and (E)] and IFN-γ [(F) and (G)] are shown. [(A) to (G)] Graphs depict at least two independent experiments. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001; one-way ANOVA/Tukey’s multiple comparison.