Relative telomere length of CD4+and CD8+T cells. The relative telomere length (RTL) of the CD4+ (A) and CD8+ (C) T cells is determined of HC (straight line) and ESRD patients not on RRT (dotted line) and lines were compared using a linear regression analysis i.e. p < 0.05 and p = 0.07 when comparing the differences between HC and non-RRT patients with respect to CD4+ RTL and CD8+ RTL respectively. The lines in A and C highlight the discrepancy between the calendar age (i.e. 40 years) of a non-RRT patient and the immunological age, by extrapolation of the value for the CD4+ and CD8+ RTL to the HC regression line, respectively. In addition, Spearmans Rho correlation coefficients (Rs) were calculated for HC and ESRD patients not on RRT to determine the strength of the association between RTL and age. Age is depicted on the X-axis and the RTL on the Y-axis. The effect of RRT on the RTL of CD4+ (B) as well as CD8+ (D) T cells was analyzed by dissecting the ESRD patients into a young (<50 years) and old (≥50 years) group and either not receiving RRT (white bars) or receiving RRT (black bars). Bars represent means + SEM. Statistical differences between the groups are shown (* p < 0.05).