Figure 3. Decreased expression of Satb1 promotes Tfh cell differentiation by derepressing Icos.

(A) Higher expression of Icos in Satb1^−/− CD4⁺ T cells (n=11). (B) Higher proportions of Icos⁺CD4⁺ T cells among lymphocytes in the absence of Satb1 (n≥19). (C) Higher proportions of Icos⁺ Tfh cells after OVA vaccination in the presence of Satb1^−/− CD4⁺ T cells (n=22). (D) (Left) Schematic depiction of Satb1 occupancy at the Icos promoter. Location of primers used for ChIP-PCR is indicated. (Right) Chromatin was immunoprecipitated with anti-Satb1 or control IgG from negatively immunopurified Satb1-competent mouse CD4⁺ T cells. Percent of input before immunoprecipitation (2.5% input values) was quantified by Real-Time Q-PCR (n=7). (E) anti-Icos / IgG (200 μg/mouse) was administered intraperitoneally in congenic Ly5.1⁺ mice reconstituted with OT-II-Satb1^f/f vs. OT-II-CD4^CreSatb1^f/f splenocytes followed by immunization with NP-OVAL in alum, and Tfh cell differentiation was quantified in spleens 5 days later (n≥12). Data are presented as median and pooled from ≥2 independent experiments. **p≤0.01, ***p≤0.001.