Extended Data Fig. 5: TFAM is required for GC B cell commitment.

(a) Counts of AP and GC B cells from NP-CGG-immunized Aicda-WT (n = 4) and Aicda-Tfam mice (n = 10). (b) Flow cytometry plot and quantification of AP and GC B cell subsets in B-WT (n = 3) and B-Tfam (n = 4) mice immunized with SRBC (enhanced protocol). (c) NP-binding rates of naïve B cells, APs, and GC B cells from Aicda-WT (n = 6) to high (NP_hi) and low (NP_lo) NP-APC conjugates. (d) Quantification of BCL6 expression (gMFI) in GC B cells from Aicda-WT (n = 4) and Aicda-Tfam mice (n = 6). (e) Heatmap of row Z-scores for gMFI of indicated mitochondrial proteins, measured by flow cytometry in TAT-Cre treated Tfam^−/− or WT iGB cells (n = 3 mice per group). (f) Live cell counts of WT and Tfam^−/− iGB cells at day 4. Results representative of two independent experiments with n = 6 technical replicates from three mice. (g) Pre-transfer tdTomato⁺Tfam^−/− and tdTomato⁻CD45.1/2⁺ WT iGB cell ratio in competitive iGB transfer experiment. (h) GFP⁺ activated OTII-Tg CD4⁺ T cells were mixed with tdTomato⁺ WT or Tfam^−/− iGBs pulsed with OVA 323-339 peptide. Percentage of GFP⁺ tdTomato⁺ doublets indicating T-B conjugates was quantified. Three technical replicates of pooled n = 2 mice shown. Representative of two independent experiments with n = 3 mice per group in total. (i) Gating and flow sort strategy for MACS-enriched CD4⁺ICOS⁺CXCR5⁺GITR⁻ T_FH cells. (j) Quantification of CD45.2⁺ GC B cells from spleens and Peyer’s patches of Aicda-WT and Aicda-Tfam (n = 5) 50:50 competitive bone marrow chimeras at day 7 following SRBC immunization, normalized to CD45.1 WT GC B cell proportions. Statistical significance was calculated by unpaired two-tailed t-test (a,b,d,j), two-tailed Mann Whitney U test (f) or two-way ANOVA with Šidák’s multiple comparison test (c,h). Data are presented as the mean ± s.e.m. Data representative of ≥2 independent experiments in all cases.

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