Figure 2: The increase of ICOS+PD-1+CXCR3+ cTfh cells correlates with the increase in Ab avidity.

(a) The correlation between the increase of ICOS+PD-1+CXCR3+ cTfh cells at day 7 post-TIV and the fold increase of Max RU/the fold decrease of Kd at day 7. Spearman R and p-value are indicated. n = 26. (b) The three groups were defined in the subjects by using the results of Kd and HI titers at day 0. (c) The correlation between the increase of ICOS+PD-1+CXCR3+ cTfh cells at day 7 post-TIV and the fold increase of Max RU/the fold decrease of Kd at day 7 in each group.