Figure S2.

Flow cytometry. (a and b) Gating strategy for phenotyping. Gating was on lymphocytes singlets that were CD20⁺ and CD3⁻CD8⁻CD16⁻Ova⁻. Anti-IgG, IgM, and IgA antibodies were used for B cell phenotype analysis. Antigen-specific cells were detected based on binding to WT RBD-PE⁺ and RBD-AF647⁺, or to Delta-RBD and Omicron BA.1-RBD. (c–e) Graphs show the frequency of IgM, IgG, and IgA isotypes expression in (c) WT RBD⁺ MBCs, (d) WT⁺Delta⁺ RBD-binding MBCs, and (e) WT⁺Omicron BA.1⁺ RBD-binding MBCs cells. (f) Gating strategy for single-cell sorting for CD20⁺ B cells for WT RBD-PE and RBD-AF647. All experiments were performed at least in duplicate and repeated twice. Statistical significance in panel c was determined by two-tailed Kruskal–Wallis test with subsequent Dunn’s multiple comparisons. *, P ≤ 0.05; ***, P ≤ 0.001; ns, not significant.