Fig. 2. STAT3 contributes to early Bcl6 induction and Tfh differentiation.

Naïve WT or STAT3^−/− SM (CD45.1⁺) cells were transferred into B6 mice that were infected with LCMV. SM cells were analyzed for Tfh differentiation at day 2 (A–B) and 3 (C–D) after infection. (A) Bcl6 histograms of WT (red) and STAT3^/− (blue) SM cells. Naïve CD4 T cells of an uninfected mouse (gray). (B) Bcl6^hiCXCR5^hi cells gated and calculated as % of total SM cells. (C) Gates indicate Bcl6⁺CXCR5⁺ SM cells at day 3 after LCMV infection. Percent of total SM cells. (D) Overlaid IL-2Rα histogram of WT (red) and STAT3^−/− (blue) SM Tfh cells, gated in Fig. 2C. IL-2Rα geoMFIs. Data are representative of three independent experiments (n = 4–5 mice per group). ** P < 0.01, *** P < 0.001. NS, not statistically different.