Early drop of circulating T cells negatively correlates with the protective immune response to Yellow Fever vaccination

Figures & data

Figure 1. Circulating CCR7-expressing CD8 and CD4 T cells transiently decrease after primary YF-17D vaccination

A. Representative flow cytometry gating strategy for the analysis of B cells and T cell subsets. CD8 versus CD4 cells were gated on live CD3⁺ lymphocytes. CD8 and CD4 T cell subset distribution was based on CCR7 and CD45RA expression to identify central memory (CM; CCR7⁺ CD45RA⁻), effector memory (EM; CCR7⁻ CD45RA⁻) and EMRA (CCR7⁻ CD45RA⁺) cells. Naïve (CCR7⁺ CD45RA⁺ CD58⁻ CD95⁻) and SCM (CCR7⁺ CD45RA⁺ CD58⁺ and CD95⁺) subsets were distinguished based on CD58 and CD95 expression. B cells were gated on live CD3- lymphocytes. B. Counts of CD8 T, CD4 T and B cells in healthy volunteer’s blood after primary YF-17D vaccination (n = 10, mean and SEM). The table below indicates the p-values comparing baseline to day 7 after vaccination (Wilcoxon test). C. Linear correlations between the CD8 T, CD4 T and B cells’ drops. The Spearman r value and the p-value are indicated on each graph. D. Counts of the various CD8 and CD4 T differentiation subsets in healthy volunteer’s blood after primary YF-17D vaccination (n = 10, mean and SEM). The p-values comparing baseline to day 7 after vaccination are indicated in the tables below (Wilcoxon test).

Figure 2. CCR7 and CD69 co-expression correlates with the reduction of T lymphocytes in the blood. A. Linear correlations between the CD8 T cell drop and the percentage of CD8 T cells expressing CD69 at baseline (n = 10) and between the CD4 T cell drop and the percentage of CD4 T cells expressing CD69 at baseline (n = 10). B Linear correlations between the CD8 T cell drop and the percentage of CD8 T cells expressing CD69 at day 7 after YF-17D primary vaccination (n = 10) and between the CD4 T cell drop and the percentage of CD4 T cells expressing CD69 at day 7 after YF-17D primary vaccination (n = 10). The Spearman r value and the p-value are indicated on each graph

Figure 3. Inter-relation between T and B lymphocyte drops, T cell responses and neutralizing antibodies after primary YF-17D vaccination

A. Representative flow cytometry gating strategy for A2/LLW+ CD8 T cells (dot plots) and CD38 expression in CD8 and CD4 T cells (histograms). “BL”: baseline, “D14”: day 14 after YF-17D vaccination, “D7”: day 7 after YF-17D vaccination. B. Linear correlations between the T and B lymphocyte drops and various parameters of immunogenicity of the YF-17 F vaccine as indicated in the y- and x-axes (n = 10). The Spearman r value and p-values are indicated on each graph. The significant correlations are highlighted as red lines.