Fig 1.
CONSORT Flow diagram.
Fig 2.
B-cell and functional antibody responses after seasonal influenza vaccination.
(A) Absolute number of plasmablasts (CD19+CD20- CD38+) in 106 live PBMCs acquired. (B) HI Geometric mean titers (GMT) for A H1N1 and H3N2, and B influenza strains at baseline (D0), 7 days (D7), 28 days (D28), and 168 days (D168) after a single dose of influenza vaccine. Data show three cohorts: saline placebo (n=7), TIIV (n=18), and ATIIV (n=17). (C) Geometric mean ratio (GMR) for all vaccine strains. Non-parametric Wilcoxon’s signed rank test was used for statistical analyses: *p < 0.05, **p < 0.01, and ***p < 0.001 compared to day 0; §p < 0.05, §§p < 0.01 and §§§p < 0.001 compared to saline placebo.
Fig 3.
Expansion of ICOS+ and PD-1+ TFH1 cells after TIIV and ATIIV vaccination.
(A) Number of CD4+ T cells expressing CXCR5 and ICOS in human PBMCs after seasonal influenza vaccination. (B and C) Number of TFH1 cells expressing ICOS and PD-1. Data show three cohorts: saline placebo (n=7), TIIV (n=18) and ATIIV (n=17) at baseline (D0), day 7 (D7) and day 28 (D28) after a single dose of influenza vaccine. Data are shown for each participant and expressed as number of cells in 106 live PBMCs acquired. Non-parametric Wilcoxon’s signed rank test was used for statistical analyses: *p < 0.05, **p < 0.01, and ***p < 0.001 compared to day 0; §p < 0.05, §§p < 0.01 and §§§p < 0.001 compared to saline placebo.
Fig 4.
H1N1-specific CD4+IL-21+ICOS+ TH cells expand 7 days after seasonal influenza vaccination.
Numbers of CD4+IL-21+ICOS+ TH cells in PBMCs stimulated overnight with A/California/7/2009 (H1N1) antigen. Data show three cohorts: saline placebo (n=7), TIIV (n=18) and ATIIV (n=17) at baseline (D0), day 7 (D7) and day 28 (D28) after a single dose of influenza vaccine. Data are shown for each subject and expressed as number of cells in 106 live CD4+ T cells acquired; mean ± SEM is shown. Non-parametric Wilcoxon’s signed rank test was used for statistical analyses: *p < 0.05, **p < 0.01, and ***p < 0.001 compared to day 0; §p < 0.05, §§p < 0.01 and §§§p < 0.001 compared to saline placebo.
Fig 5.
H1N1-specific CD4+IL-21+ICOS+ TH cells subsets expressing or not CXCR5 expand after influenza vaccination.
Number of CD4+IL-21+ICOS+ TH cells, showing a CXCR5+ (black) or CXCR5- (gray) phenotype, in vaccinated participants after overnight stimulation with A/California/7/2009 (H1N1) antigen or SEB. Data show saline placebo (n=7), and merged TIIV (n=18) and ATIIV (n=17) cohorts at baseline (D0), day 7 (D7) and day 28 (D28) after a single dose of influenza vaccine. Data are expressed as number of cells in 106 live CD4+ T cells; mean ± SEM is shown. Non-parametric Wilcoxon’s signed rank test was used for statistical analyses: *p < 0.05, **p < 0.01, and ***p < 0.001 compared to day 0.
Fig 6.
TFH1 ICOS+ cells predict functional antibody responses.
Correlations between the number of total circulating CD4+ TFH1 ICOS+ cells and the maximum DHI responses observed across the three influenza strains represented in the vaccine, measured at (A) day 28 and (B) day 168 after immunizzation. Dashed lines represent the least squares regressions fit to the data. R: Pearson product-moment correlation coefficient. p: correlation-associated p value.
Fig 7.
H1N1-specific CD4+IL-21+ICOS+CXCR5+ TFH cells predict functional antibody responses.
Correlations between the number of H1N1-specific CD4+IL-21+ICOS+CXCR5+ TFH cells and H1N1-specific DHI responses measured at (A) day 28 and (B) day 168 after immunizzation. Dashed lines represent the least squares regressions fit to the data. R: Pearson product-moment correlation coefficient. p: correlation-associated p value.
Table 1.
Correlation between cell subsets and DHI titers.