FIGURE 4.

Plasmablast responses following YFV 17D vaccination. (A) CD38^high and CD27^high coexpression on CD19⁺CD20^−/low B cells define plasmablasts in freshly isolated PBMCs over time. Displayed is one representative study subject along with IgA, IgG, and Ki67 expression on each subset. (B) Total plasmablast and plasmablast (C) IgA⁺, (D) IgG⁺, and (E) IgA⁻IgG⁻ subset frequencies. Median with 95% confidence interval (CI) are plotted at days 0, 7, 14, 28, and 90 following vaccination. (F) Proportions of Ig expression shift on plasmablasts over time. (G) Ki67 expression in total plasmablasts and (H) IgA⁺, (I) IgG⁺, and (J) IgA⁻IgG⁻ and subsets plotted as median with 95% CI over time. For all plasmablast graphs, excluding IgA⁺, IgA⁺ Ki67⁺, IgA⁻IgG⁻, and IgA⁻IgG⁻ Ki67⁺ subsets, day 0, n = 24; day 7, n = 15; day 14, n = 22; day 28, n = 18; and day 90, n = 12. For IgA⁺ and Ki67⁺ IgA⁺ plasmablasts, day 0, n = 11; day 7, n = 15; day 14, n = 20; day 28, n = 16; and day 90, n = 10. Statistical analysis was performed using nonparametric Wilcoxon matched-pairs signed-rank test. *p < 0.05, **p < 0.01, ***p < 0.001.