Sara van den Berg

98 Chapter 4 panel). G) Percentage of influenza virus specific CD8 + T-cells in all CMV- and CMV+ individuals. H) Percentage of influenza specific CD8 + T-cells in CMV- and CMV+ individuals categorized in young and old individuals. Tetramer for matrix protein-1 GILG-epitope was used. All individuals were HLA-A2 positive. Median is presented in each figure. Differences between groups were compared by Mann Whitney U test. Figure 2. Characterization of the influenza virus-specific CD8 + T-cell response after infection shows no impairment by CMV-seropositivity, but enhancement of the early influenza virus-specific CD8 + T-cell re- sponse. A) Percentage of influenza specific CD8 + T-cells in HLA-A2 positive individuals upon influenza infection. Tetramer for matrix protein-1 GILG-epitope was used B) The percentage effector memory (EM) cells of influen- za-specific CD8 + T-cells upon influenza infection. C) Influenza-specific IFN γ T-cell response upon influenza infection. D) Percentage of influenza specific T-cells in HLA-A2 positive individuals upon influenza infection for CMV- and CMV+ individuals. E) The percentage effector memory (EM) cells of influenza specific T-cells upon influenza virus infection for CMV+ and CMV- individuals. F) Influenza virus-specific IFN γ T-cell response upon influenza infection for CMV- and CMV+ individuals. Percentage of influenza specific CD8 + T-cells was measured using a tetramer for matrix protein-1 GILG-epitope. Influenza-specific T-cell response to overlapping influenza matrix-protein 1 peptide pools was measured by IFN γ ELISPOT spots. Wilcoxon test was used to compare T-cell responses of individuals in time and Mann-Whitney U test was used to compare CMV- and CMV+ individuals. Correlation between CMV-specific immune responses and IFN γ response to influenza virus was tested by Spear- man correlation. T-cell IFN γ responses are presented per 1x10 6 PBMCs. When corrected for the percentage of T-cells among all lymphocytes, the influenza virus T-cell response was again higher at 2 weeks (p=0.022) compared to 8 weeks, albeit not significant (p=0.059) ( Supplementary figure 2A left panel ). The average increase in the IFN γ response to influenza was comparable between H3N2 influenza-infected and H1N1 influenza-infected individuals (data not shown)