Figure 4. Progeny of the primary GC B cells engage in secondary GCs more efficiently after local boosts than after distal boosts.

AID-Cre-EYFP mice were primed and boosted with H1 SI-06 as shown in Figure. 1A. Primed animals were given tamoxifen i.p. daily through days 8–12 after priming. In some experiments, primed animals received MR-1 Abs or control IgGs 4 weeks after the priming. Representative flow diagrams (A), and frequency (B) and number (C) of YFP⁺ GC B cells in the draining LNs are shown. (B and C) Each dot represents an individual mouse. Horizontal bars represent geometric mean. ***, p < 0.001; *, p < 0.05; n.s., p > 0.05 by Kruskal-Walis test with Dunn’s multiple comparisons. (D) Distributions of AvIn values for clonal IgGs from GC B cells following ipsilateral boosts are shown (left, YFP⁺ and YFP⁻ combined, n = 227; middle, YFP⁺, n = 109; right, YFP⁺ receiving MR-1, n = 71). Horizontal bars represent geometric mean. Dotted line represents AvIn = 0.1, our cutoff for “high avidity”. Combined data from 4 independent experiments are shown. No statistical significance was seen among groups by Kruskal-Walis test with Dunn’s multiple comparisons. (E) Distributions of the number of V_H point mutations in YFP⁺ (n = 399) and YFP⁻ (n = 618) secondary GC B cells following ipsilateral boosts. Each dot represents an individual IgG⁺ sample. Horizontal bars represent mean. ***, p < 0.001 by Mann-Whitney’s U test.