Figure 2.

Changes in the polarisation of circulating Tfh cells after yellow fever vaccination (a, b) PBMCs isolated before (day 0) and at the indicated time points after YF‐17D vaccination were analysed by flow cytometry (see Supplementary figure 1 for the gating strategy). Representative contour plots and quantification of frequencies of (a) cTfh cell subsets and (b) activated CD38⁺ cTfh cell subsets identified according to CXCR3 and CCR6 expression are shown for the indicated time points. (c) Frequencies of cytokine‐expressing CD38⁺ cTfh cells were measured by intracellular antibody staining after re‐stimulation ex vivo with PMA/ionomycin on day 14 after YF‐17D vaccination. (a, b) Pooled data from four independent experiments with 5 to 10 study participants each are presented as Tukey boxplots showing the median with the 25th and 75th percentile (n = 33) and whiskers and outliers calculated as highest and lowest observation below/above 1.5 times interquartile range. Data points below/above 1.5 times interquartile range are displayed individually. Statistical analysis was performed using RM one‐way ANOVA and Dunnett's multiple comparison analysis to compare indicated time points to day 0. *P < 0.0332, **P < 0.0021, ***P < 0.0002, ****P < 0.0001. (c) Representative data of one of four separately performed experiments are shown as mean and SEM, with each dot representing one donor (n = 6).