Figure 2.

T-bet is required for TFH cell expansion during acute viral infection. WT and Tbx21^−/− mice were infected with LCMV. Splenocytes were isolated and analyzed by flow cytometry and RT-qPCR at day 8 post infection. (A) Summary of T-bet expression (showed as MFI) of TFH cells (CD44⁺CXCR5⁺) and TH1 cells (CD44⁺CXCR5⁻) in WT and Tbx21^−/− mice. (B) T-bet gene expression relative to Hprt mRNA of sorted TFH and TH1 cells from WT and Tbx21^−/− mice was assessed by RT-qPCR. (C–E) Representative Flow cytometry of TFH cells (CD44⁺CXCR5⁺) (C), tetramer-positive CD4⁺ T cells (D), and tetramer-positive TFH cells (E) in WT and Tbx21^−/− mice (left), and the summary of percentages and number of these cell subsets (right). Numbers adjacent to outlined areas indicate percent of each cell subset in parent subset. ns, not significant; ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ^****P < 0.0001 (unpaired two-tailed t-test). Data are representative of three independent experiments with 3–5 mice per group (error bars, SEM).