Influence of hemodialysis on circulating CD4lowCD25high regulatory T cells in end-stage renal disease patients

Immunodeficiency of end-stage renal disease (ESRD) is caused by several factors including uremic toxins and biocompatibility reactions due to the repeated hemodialysis (HD) procedure. It has also been suggested that poor T cell responses could be associated with the increased number of regulatory T cells (Tregs) which are necessary to limit the function of activated T cells. The aim of the study was to determine the proportion of CD4(+)CD25(+) cells (activated T cells) to CD4(low)CD25(high) cells (Tregs) within the CD4(+) population in ESRD patients. Two groups of ESRD patients, predialysis patients treated conservatively and patients undergoing hemodialysis (HD), as well as healthy controls were included in the study. Percentages of activated and regulatory T cells were determined ex vivo with flow cytometry based on the expression of CD4 and CD25 antigens. HD patients showed an increased percentage of CD4(+)CD25(+) cells when compared with healthy controls, while there was no difference in the percentage of CD4(low)CD25(high) cells between the patient groups. In our opinion, the repeated hemodialysis procedure significantly disturbs the balance between activated T cells and regulatory T cells in ESRD patients. Lack of Treg mobilization and chronic stimulation of T cells may contribute to the immune deficiency observed in these patients.