(a) Gating strategy for AID-Confetti single GCs shown in (b,c), Figs. 2a and 3d–e, and Extended Data Fig. 6a–b and 8a. (b,c) Additional Igh sequence relationships among B cells from high-NDS GCs (b) and one low-NDS GC (c). Details as in Fig. 2a. Scalebars, 50 μm. In (c), each tree is a separate clone (defined as a unique V(D)J rearrangement). Only clones with > 5 cells are shown (grey slices). (d) Gating strategy for bacterial flow cytometry, performed in (e), Figs. 2b and 3f, h–i, and Extended Data Fig. 6d. (e) Binding of recombinant mAbs to fecal bacteria isolated from SPF mice by flow cytometry. Plots gated as in (d). All plots are representative of data repeated in at least two separate experiments. (f) Reactivity summary of SPF mAbs assayed by ELISA against food protein extracts, autoantigens (anti-nuclear antibody, ANA), and a 5-antigen polyreactivity panel. Shown are background-subtracted OD 450nm values. Data representative of assays repeated in at least 3 separate experiments.