Figure 1. E4BP4 is more abundantly expressed in Tfh cells.

(A) Analysis of naive CD4⁺ T cells from 8-week-old C57BL/6 mice stimulated in vitro under Th0, Th1, Th2, Th17, Treg, and Tfh cell–polarizing conditions for 3 days (Th0, Th1, Th17, Treg, and Tfh cells) or 5 days (Th2 cells) by flow cytometry for mean fluorescence intensity (MFI) of E4BP4 (n = 9). (B) mRNA expression of E4bp4 in T cell subsets indicated in A (n = 6). (C) Naive CD4⁺ T cells, anti-CD3/CD28–activated CD4⁺ T cells, and in vitro–polarized Tfh cells were stained by anti-E4BP4 (red) and DAPI (blue) and analyzed by confocal microscopy. Scale bar: 5 μm. (D) Statistical intensity of E4BP4 in nuclei (n = 6). (E) Flow cytometric analysis of E4BP4 expression in mice CD4⁺ T cells (n = 10). (F) Gating strategy of CXCR5⁺PD-1⁺(Tfh) or CXCR5^–PD-1^– (non-Tfh) cell phenotype in CD4⁺ T cells from KLH immunized C57BL/6 mice. Analysis of E4BP4 and BCL6 expression (MFI) is shown in the right panel. (G) Statistical analysis of F (n = 10). (H) Gating strategy of human tonsillar CD45RO⁺ memory/effector or CD45RO^– naive CD4⁺ T cells. CD45RO⁺ cells were subsequently divided into CXCR5^lo, CXCR5^int, and CXCR5^hi gates. (I and J) Representative histograms of CXCR5, BCL6, PD-1, and E4BP4 MFI expressions in subsets outlined in H (n = 10). Data are representative of 3 independent experiments. For A, B, D, and J, 1-way ANOVA with Dunnett’s post hoc test, E and G with Student’s t test. *P < 0.05; **P < 0.01; ***P < 0.001.