Dialysis treatment and regulatory T cells

Sir, We read with attention the paper by Hendrikx et al., recently published in Nephrology Dialysis and Transplantation [1]. The authors observed a lower number and an impaired function of both CD4+CD25bright+ and Foxp3+ T cells in end-stage renal disease patients, especially in haemodialysis (HD), when compared to healthy controls. These results are very interesting since it has been demonstrated that these specific T cell populations, also known as regulatory T cells (Treg), play a key role in the control of the immune system [2,3]. Here, we report the results of a study which are in contrast with the ones by Hendrikx et al. In order to evaluate the effects of dialytic treatment on Treg cells subset, we studied seven patients (60.4 ± 10.3 years, m/f: 4/3) on standard thrice-weekly bicarbonate HD with a low-flux membrane [cuprophane (CU)] for at least 6 months. A whole blood sample was harvested before and after the dialysis (PRE and POST, respectively). Peripheral blood mononuclear cells (PBMC) were isolated from blood samples by lymphoprep gradient density centrifugation. Flow cytometry was performed in order to evaluate Treg cells, using anti-CD4, CD25 and Foxp3 mAbs (BD Biosciences, San Jose, USA). According to flow cytometry results, we identified CD4+CD25bright+ and Foxp3+ cells.