Figure 4. T-bet-deficient CD4⁺ T cells promote an exacerbated Th17-type inflammatory response.

C57BL/6 Rag1^−/− mice were injected i.p. with 4x10⁵ CD4⁺CD25⁻CD45RB^hi T cells from C57BL/6 WT or Tbx21^−/− donors. Mice were killed when recipients of Tbx21^−/−T cells developed clinical signs of disease (4–6 weeks). (a) Representative plots of cytokines and transcription factors in WT or Tbx21^−/− colonic CD4⁺ T cells. (b) Frequency of IL-17A⁺, IL-17F⁺, IL-22⁺, GM-CSF⁺ or IFN-γ⁺ colonic T cells in WT or Tbx21^−/−. (c) quantitative reverse transcription PCR (qRT-PCR) analysis of mRNA levels of indicated genes in colon tissue homogenates. (d) Total number of neutrophils (CD11b⁺ Gr1^high) in the colon. (e) Primary epithelial cells were isolated from the colon of steady state C57BL/6 Rag1^−/− mice and stimulated with 10 ng ml⁻¹ cytokines for 4 h after which cells were harvested and analysed by qRT-PCR for the indicated genes. Data in b–d represent pooled results from two independent experiments (n=14 for WT, n=11 for Tbx21^−/−). Bars are the mean and error bars represent s.e.m. Data in e are pooled results from four independent experiments, bars are the mean and error bars represent s.e.m. *P<0.05, **P<0.01, ***P<0.001 as calculated by Mann–Whitney U test.