ESRD-associated immune phenotype depends on dialysis modality and iron status: clinical implications

Background: End-stage renal disease (ESRD) causes premature ageing of the immune system. However, it is not known whether hemodialysis (HD) and peritoneal dialysis (PD) similarly affect the T cell system. Methods: The aim of our study was to analyse whether dialysis modality may mitigate ESRD-induced immune senescence. We explored a large population of patients (675 ESRD patients) and both confirmed and refined the results in a second cohort (84 patients). Results: HD patients exhibited higher inflammatory monocytes counts (44/mm(3) (1-520) vs 36/mm(3) (1-161); p = 0. 005). Patients on HD also had higher frequency of CD8 T cells (24% (7-61) vs 22% (8-42); p = 0.003) and reduced CD4/CD8 ratio. Such results were confirmed in the second cohort. Moreover, both CD4 + CD57 + CD28-(3.25% (0-38.2) vs 1.05% (0-28.5); p = 0.068) and CD8 + CD57 + CD28-(38.5% (3.6-76.8) vs 26.1 (2.1-46.9); p = 0.039) T cells frequencies were increased in HD patients. Telomere length did not differ according to dialysis modality, but was inversely related to ferritin levels (r = -0.33; p = 0.003). There was a trend towards higher telomerase activity in PD patients (11 +/- 13 vs 6 +/- 11; p = 0.053). Thymic function was not different in PD and HD patients. Patients on PD before transplantation had a higher risk of acute rejection after kidney transplantation (HR, 1.61; 95% CI, 1.02 to 2.56; p = 0.041). Conclusions: More pronounced inflammation with hemodialysis may induce premature aging of the immune system. This observation correlates with a lower risk of acute kidney rejection in patients previously on HD. Clinical consequences in patients maintained on dialysis should be determined.