Fig. 3: IRF1 expression in DCs controls antigen-specific T_H17 differentiation.

a–c 2 × 10⁴ BMDCs from wild-type, Irf1^−/−, Irf3/7^−/−, and Irf7^−/− mice were stimulated with PBS, 20 μg/ml of OVA or 20 μg/ml of OVA plus 25 μg/ml of c-di-GMP for 18 h and co-cultured for 4 days with 1 × 10⁵ MACS-sorted naïve OT-II T cells. Production of IL-17A and IFN-γ was determined in supernatant of BMDC from a wild-type or Irf1^−/− or b Irf3/7^−/− mice co-cultured naïve OT-II cells. n = 4. ***p < 0.001. c Measurement of IL-17A and IFN-γ in supernatant of BMDC from wild-type, Irf1^−/−, Irf3/7^−/−, and Irf7^−/− mice co-cultured naïve OT-II cells. n = 3. ***p < 0.001. d and e wild-type (n = 4) and Irf1^−/− (n = 4) mice were (i.v.) injected 2 × 10⁶ Cell trace Violet labeled naïve OT-II cells on day 0. On day 1, the mice were immunized with OVA plus c-di-GMP (i.n.). d Cell proliferation analysis in adoptively transferred OT-II cells from wild-type and Irf1^−/− mice 5 days after immunization in cervical lymph nodes. n = 4. ***p < 0.001. e Il17a and Ifnγ mRNA expression was quantified by qRT-PCR in sorted Cell trace Violet positive OT-II cells after 5 days of immunization. n = 4, ***p < 0.001. f qRT-PCR analysis of Il17a and Ifnγ gene expressions in sorted CD4⁺ T cells in MLN from wild-type, Tmem173^−/−, and Irf1^−/− mice immunized with OVA plus c-di-GMP through i.p. route. n = 3. **p < 0.01 and ***p < 0.001. g qRT-PCR analysis of the indicated genes in BMDCs from wild-type, Tmem173^−/−, Irf1^−/−, Irf7^−/−, and Irf3/7^−/− mice after 18 h stimulation by 50 μg of c-di-GMP. n = 4. *p < 0.05, ***p < 0.001. p-values, one-way c, f, two-way a, b, g ANOVA followed by Tukey’s multiple-comparisons test or unpaired two-tailed Student’s t-test d, e. Data are representative of two d–f or three a, b, c, g independent experiments.