Fig. 4: Correlation between frequency of RBD-specific B cells and neutralising antibody response to COVID-19 vaccination.

a Representative flow cytometry plots displaying RBD-specific B cell populations amongst total CD19⁺ B cells for different study groups 0, 8, 21 and 105 days (D0, D8, D21 and D105) after the second dose of BNT162b2 vaccine. b Frequencies of RBD-specific B cells amongst all CD19⁺ B cells in HC, IEI and ICB patients at days 0, 8, 21 and 105. Each dot represents a single individual (healthy controls (HC, D0 = 10, D8 = 10, D21 = 10, D105 = 7), grey; patients with rare inborn errors of immunity (IEI, D0 = 7, D8 = 7, D21 = 8, D105 = 6): (NFKB1) red, (CTLA-4 and unclassified) orange; patients treated with ICB (ICB, D0 = 19, D8 = 19, D21 = 19, D105 = 17), blue). Two-way ANOVA with Tukey’s multiple comparisons test for statistical analysis. c Correlations between frequencies of RBD-specific B cells amongst all CD19⁺ B cells at day 0 and NT₅₀s at days 8, 21 and 105. Two-tailed Spearman’s rank correlation coefficients (rho) and p values are shown, together with indicative linear regression lines. d Correlations between frequencies of ABCs amongst B cells at day 0 and frequencies of RBD-specific B cells at days 8, 21 and 105. Two-tailed Spearman’s rank correlation coefficients (rho) and p values are shown, together with indicative linear regression lines. e UMAP projection of total B cells from all donors at all time points displaying memory B cell (MBCs, purple) and plasmablast (PBs, green) populations. f RBD-specific B cells with MBC (purple) or PB (green) phenotype are shown at days 0, 8, 21 and 105 (columns) for HC (top), IEI (middle) and ICB (bottom) groups. g Kinetics of RBD-binding cell frequencies amongst MBCs or PBs. Statistical significance between groups was determined using ordinary one-way ANOVA. Samples with no detectable levels of RBD-specific cells are plotted at an arbitrary value of 10^-4 in b and 10^-3 in g.