Bcl6 controls generation of GC Tfh, but not cytokine profile, in responding effector cells.

(A) Naïve (CD44loCD25-) CD4 T cells (2x106) from either Bcl6fl/fl CD4Cre (Bcl6 cKO) or Bcl6fl/fl (WT) were labeled with cell trace violet (CTV) and adoptively transferred into Ly5.1 (CD45.1) congenic mice, followed by P. chabaudi infection. On day 7 post-infection, splenocytes were harvested and stained with (B) CD4, CD45.2, CTV, (C, D) PD-1, CXCR5, (E) IFN-γ, IL-21, and (F) IFN-γ, IL-10. (B) Plots showing the gating on responding CD4+CD45.2+CTV- T cells. (C) Graph shows percentages for individual recipients of effector T cell subsets. No CD45.2+ CXCR5hiPD-1hi GC Tfh cells were detected in any recipient of Bcl6 cKO T cells. (D) Bar graph shows CXCR5 MFI of CD4+CD45.2+CTV- donor cells. (E) Plots and bar graph of average IFN-γ and IL-21 cytokine producers in the responding donor cells (CD45.2+CTV-) in recipients of WT and Bcl6 cKO T cells. (F) Dot plot showing intracellular cytokine staining. Data are representative of three independent experiments with 4–5 animals per group. Numbers within plots represent mean percentages. Statistical significance was obtained using Students t-test. Error bars represent the SEM; ★p ★★★p