Figure 6.

Activation of cT_FH and antibody secreting cells by vaccination with QIV. (a) Gating strategy for CD4⁺CXCR5⁺CXCR3⁺ cT_FH. Panels show (b) frequency of ICOS⁺PD-1⁺ cT_FH, (c) frequency of ICOS⁺PD-1⁺ cT_FH expressing CD38. (d) Gating strategy for CD4⁺CD32⁺ T cells and (e) frequency of CD4⁺CD32⁺ T cells across time points. (f) Frequency of CD4⁺ CD32⁺ CXCR5⁺ ICOS⁺ T cells at all time points. (g) Panels show correlation of activated cT_FH cells at Day 7 with fold change at Day 28 of HAI titre for A/H1N1 (top left), A/H3N2 (top right), B/Brisbane (bottom left) and B/Phuket (bottom right). (h) Correlation of CD38⁺cT_FH cells at Day 7 with fold change at Day 28 of HAI titre for A/H1N1 (top left), A/H3N2 (top right), B/Brisbane (bottom left) and B/Phuket (bottom right). (i) Gating strategy for CD27^hiCD38^hiCD19⁺ antibody secreting cells (ASC). (j) Frequency of CD27^hiCD38^hiCD19⁺ ASCs and (k) frequency of CXCR3⁺ASCs at each time point. Spearman’s rank correlation coefficient (r_s) is shown. Intra-individual comparisons between time-points were performed using Friedman test; (p value below graph) and p values of the Dunn’s multiple comparisons test (above graph). Individual data points are shown on graph panels: HC, filled green circles; E-HIV, filled orange circles; C-HIV, open orange circles.