Fig. 2

Cytokine expression pattern of EBV- and HCMV-reactive CD4 (a) and CD8 (b) T cells. Pie charts represent the relative functional composition of total EBV- and HCMV-reactive CD4 (a) and CD8 (b) T-cell responses upon stimulation of freshly isolated PBMC of 30 EBV- and 19 HCMV-seropositive individuals with T-activated proteins versus the corresponding peptide pools. Each pie slice corresponds to the proportion of T cells positive for one, two or three cytokines (IFN-γ, TNF, and/or IL-2, respectively) (mono-, bi-, and tri-functional T-cell responses, respectively). Individual cytokine expression pattern of mono-, bi-, and tri-functional T-cell responses are illustrated by the concentric colored arcs surrounding the pie chart. Color codes defining the number (slices) and type (arcs) of expressed cytokines are indicated in the figure legend. Statistical analyses of differences of proportions of mono-, bi-, and tri-functional T-cell responses upon stimulation of either PP or TP were done with paired Wilcoxon signed rank tests. PP peptide pool, TP T-activated protein. *p < 0.05; **p < 0.01; ***p < 0.001