Fig. 3. Both STAT1 and STAT3 are required for early Tfh differentiation of CD4 T cells.

(A) Ctrl- or STAT1^KD SM (CD45.1⁺) cells were stimulated with IL-6 for pSTAT stainings. Overlaid histograms of pSTAT1 and pSTAT3. (B) Ctrl- or STAT1^KD SM cells were transferred into B6 mice that were infected with LCMV. Gates indicate Bcl6^hiCXCR5^hi at day 2 after infection. % of Bcl6⁺CXCR5⁺ Tfh cells among total SM cells. (C–E) Ctrl-, STAT1^KD, STAT3^−/−, or STAT3^−/−STAT1^KD SM cells were transferred into B6 mice. SM analyzed at day 3 after infection. (C) Gates indicate Bcl6⁺CXCR5⁺ Tfh cells. (D) % of Tfh cells calculated. (E) CXCR5 MFIs were normalized with cell size of donor cells (CXCR5_MFI/FSC_MFI). Data are representative of two (C–E) and three (A–B) independent experiments (n = 4–5 mice per group). ** P < 0.05, *** P < 0.01.