FIG 1.

The majority of primed CD4 T cells acquire Tfh lineage markers following clonal expansion. Sorted naive WT OT-II cells (CD45.1) were transferred into congenic (CD45.1) immunocompetent mice (1 × 10⁵ cells/mouse). On the next day, the mice were immunized with OVA-LPS emulsified in IFA subcutaneously in the hind footpads. (A) The kinetics of OT-II T cell expansion and CXCR5⁺ PD-1⁺ OT-II cells at given time points (left) and the mean ± SEM percentage of expanded cells from three independent mice (right) are shown. (B) The relative expression of mRNA for transcription factors from sorted OT-II cells was evaluated by qPCR. (C and E) Flow plots of expanded OT-II T cells expressing lineage-specific transcription factors BCL6 and/or T-bet (C) or RORγt (E) on day 7 and day 14 postimmunization. (D and F) The mean ± SEM percentages of expanded OT-II cells expressing BCL6 and/or T-bet (D) and RORγt (F) on day 7 and day 14 postimmunization. Data are representative of those from three independent experiments with three mice for each group. (A, B, D, and F) P values were determined by an unpaired t test. *, P > 0.05; **, P > 0.01, ***, P > 0.001. TF, transcription factor; Ab, antibody.