Fig. 1: Conditional ablation of METTL3 impairs T_FH differentiation and GC responses.

a, b Flow cytometry analysis of CD44⁺CXCR5⁺ T_FH cells and CD44⁺CXCR5^– T_H1 cells, gated on splenic CD4⁺ T cells from Ctrl and Mettl3^fl/flCd4-Cre mice on day 8 post infection (8 dpi). Summary of the frequency and cell numbers of indicated cell subsets are shown in b (n = 5 per group). c, d Flow cytometry analysis of PD-1^hiCXCR5⁺ GC T_FH cells (top panel), ICOS^hiCXCR5⁺ GC T_FH cells (middle panel), and Bcl-6^hiCXCR5⁺ GC T_FH cells (bottom panel), gated on splenic CD44^hiCD62L^loCD4⁺ T cells from Ctrl and Mettl3^fl/flCd4-Cre mice on 8 dpi. Summary of the frequency and cell numbers of indicated cell subsets are shown in d (n = 5 per group). e, f Flow cytometry analysis of splenic GL-7⁺Fas⁺ GC B cells (top panel) and IgD^loCD138⁺ plasma cells (bottom panel) on 8 dpi. Summary of the frequency and cell numbers of GC B cells and plasma cells are shown in f (n = 3 per group). g Immunofluorescent staining of spleens from Ctrl and Mettl3^fl/flCd4-Cre on 8 dpi. Green: PNA; Red: IgD; scale bar: 10 μm. h Analysis of LCMV-specific IgG concentration in serum on 8 dpi (top) and on 56 dpi (bottom) by ELISA (day 8: n = 12 for Ctrl group, n = 10 for Mettl3^fl/flCd4-Cre group; day 56: n = 5 per group). Data are representative of at least three independent experiments. Error bars indicate standard error of the mean. P value was calculated by unpaired two-tailed Student’s t test.