Fig. 4

Correlation between frequencies of pT_FH and CD4⁺ IL-21⁺ T cells. The inverse correlation (Spearman’s rho: − 0.86, p < 0.001) between frequencies of CCR7^low and PD-1^high pT_FH (among CD4⁺ CD45RA⁻ CXCR5⁺ T cells) and CD4⁺ IL-21⁺ T cells, collected prior to, seven and 21 days after vaccination (n = 5 subjects and 15 time points). The three time points for the patient are depicted as triangles