Elderly individuals show an increased frequency of CMVpp65-specific CD8 T cells. The frequency of A2/CMVpp65 pentamer-positive CD8 T cells was analysed in young, middle aged and elderly donors. Data are presented as diagrams of boxes; the lower boundary of the box indicates the 25th percentile and the upper boundary the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles. A line within the box marks the median. Outliers are represented as individual points. P values lower than 0.05 were considered statistically significant.