Influence of end stage renal disease on CD28 expression and T cell immunity.

BACKGROUND T-cell immunity is affected in End Stage Renal Disease (ESRD). However, whether this happens at pre- or post-dialysis stage and what is the impact of different renal replacement methods, remains unclear. We investigated the alterations of T-cell subtypes in patients at pre-dialysis ESRD and their further changes during dialysis. METHODS CD4+, CD8+, CD4+CD28null and CD8+CD28null T-cells were analyzed in 40 ESRD patients at two different time points, i)the day started on dialysis (ESRD-T0)and ii)six months later (ESRD-T6), while being on hemodialysis(HD) or continuous ambulatory peritoneal dialysis(CAPD). Twenty-five age matched healthy volunteers served as controls. RESULTS CD4+ and CD8+ T-cells were significantly reduced in ESRD-T0 patients compared to controls, 604(105-3551) vs. 943(584-1867)μ/L, p=0.001, and 352(103-1561) vs. 422.4(263-1453)μ/L, p=0.05, respectively. However, proportions of CD4+CD28null and CD8+CD28null cells were significantly increased, 6.4(0.3-30)% vs. 2.7(0.1-7.8)%, p=0.04 and 58.2(12.8-85.4)% vs. 39(7.8-57.1)%, p=0.01,respectively. Proportion of CD4+CD28null cells showed significant correlation with serum CRP (r=0.4, p=0.04) and albumin levels (r=-0.5, p=0.007) in ERSD patients. ESRD-T0 patients with cardiovascular disease (CVD) had increased CD4+CD28null and CD8+CD28null proportions, 8.6(1-30)% vs. 2.1(0.1-19.8)%, p=0.04 and 62.5(12.8-85.4)% vs. 45.5(5.7-73.7)%, p=0.02, respectively, compared to those without. Six months later, both CD4+CD28null and CD8+CD28null T-cells were increased in HD compared to CAPD patients, by +110.11(-27.1 to 311.4)% vs. -28.1(-100 to 30)%, p=0.003 and +55.23(-29.06 to 197.93)% vs. -8.34(-54.99 to 66.72)%, p=0.05 respectively. CONCLUSIONS CD4+CD28null and CD8+CD28null T-cells are increased at pre-dialysis ESRD, and correlate with chronic inflammatory markers and the presence of CVD. Dialysis methods seem to have different impact on these subpopulations.