Fig. 2: METTL3 intrinsically controls T_FH differentiation and GC responses.

a Scheme of adoptive transfer model. 5 × 10⁶ CD45.1⁺ SMARTA cells were adoptively transferred into CD45.2⁺ Mettl3^fl/flCd4-Cre mice or Ctrl host mice, followed by LCMV-Armstrong infection within 24 h. b, c Flow cytometry analysis of CD45.1⁺ SMARTA or CD45.2⁺ host T cell-derived CD44⁺CXCR5⁺ T_FH and CD44⁺CXCR5^– T_H1 cells, gated on splenic CD4⁺ T cells from host mice on day 8 post viral infection. Frequency and numbers of CD44⁺CXCR5⁺ T_FH cells and CD44⁺CXCR5^– T_H1 cells are shown in c (n = 5 per group). d, e Flow cytometry analysis of splenic PNA⁺Fas⁺ GC B cells (top panel) and IgD^loCD138⁺ plasma cells (bottom panel) from host mice on 8 dpi. Summary of the frequency and cell numbers of GC B cells and plasma cells are shown in e (n = 6 per group). f Immunofluorescent staining of spleens from Ctrl or Mettl3^fl/flCd4-Cre host mice on 8 dpi. Green: PNA; Red: IgD; scale bar: 10 μm. g Analysis of LCMV-specific IgG concentration in serum on 8 dpi by ELISA (n = 5 for Ctrl group, n = 5 for Mettl3^fl/flCd4-Cre group, n = 6 for Ctrl host group, n = 6 for Mettl3^fl/flCd4-Cre host 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 (e) or two-way ANOVA coupled with multiple comparisons (c, g).