Background: End-stage renal disease (ESRD) is associated with alterations in T-cell immunity, including increased CD28null and reduced regulatory T cells (Tregs). However, whether immune disturbances are due to ESRD or primary disease is not yet clear. As diabetes mellitus is the leading cause of ESRD, we evaluated its impact on the immune profile of ESRD patients. Methods: CD28null, Tregs, and natural killer cells were initially analyzed by flow cytometry in 30 predialysis ESRD patients due to diabetes (DM), 30 non-DM (NDM), and 25 healthy controls. Measurements were repeated after 6 months on hemodialysis (HD) or peritoneal dialysis (CAPD). Results: The percentage of CD4 + CD28null cells, CD8 + CD28null cells, and Tregs showed significant differences in DM, NDM, and controls; mean rank 33.71 vs. 25.68 vs. 18.88, p = 0.006, 37.79 vs. 28.82 vs. 17.08, p = 0.008, and 20.79 vs. 26.12 vs. 41.33, p = 0.001, respectively. DM vs. NDM had increased CD4 + CD28null and CD8 + CD28null cells, 11.5% (1.5%–24%) vs. 4.1% (0–42.3%), p = 0.02 and 61.3% (24%–76%) vs. 43% (5.7%–85%), p = 0.04, respectively. After 6 months on HD but not CAPD, DM showed a significant further increase in CD4 + CD28null cells, from 30 (14–100) to 52.7 (15–203), p = 0.02; and CD8 + CD28null cells, from 137 (56–275) to 266 (103–456), p = 0.01. Conclusions: Diabetes mellitus affects T-cell subtypes even at predialysis stage, though changes become more prominent after commencement on HD.

End-stage renal disease (ESRD) is followed by alterations in adaptive immunity. The aim of this study was to evaluate B lymphocyte subtypes in ESRD patients before and after hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD). Patients and Methods. CD5, CD27, BAFF, IgM and annexin were evaluated by flow cytometry on CD19+ cells in ESRD patients (n = 40), at time of initiating HD or CAPD (T0) and 6 months later (T6). Results. A significant reduction in ESRD-T0 compared to controls was noticed for CD19+, 70.8 (46.5) vs. 171 (249), p < 0.0001, CD19+CD5−, 68.6 (43) vs. 168.9 (106), p < 0.0001, CD19+CD27−, 31.2 (22.1) vs. 59.7 (88.4), p < 0.0001, CD19+CD27+, 42.1 (63.6) vs. 84.3 (78.1), p = 0.002, CD19+BAFF+, 59.7 (37.8) vs. 127.9 (123.7), p < 0.0001 and CD19+IgM+ cells, 48.9 (42.8) vs. 112.5 (81.7) (K/μL), p < 0.0001. The ratio of early/late apoptotic B lymphocytes was reduced (16.8 (10.9) vs. 110 (25.4), p = 0.03). CD19+CD5+ cells were the only cell type with an increased proportion in ESRD-T0 patients (2.7 (3.7) vs. 0.6 (1.1), p < 0.0001). After 6 months on CAPD or HD, CD19+CD27−(%) and early apoptotic lymphocytes were reduced further. The HD patients also showed a significant increase in late apoptotic lymphocytes, from 1.2 (5.7) to 4.2 (7.2) K/mL, p = 0.02. Conclusions. B cells and most of their subtypes were significantly reduced in ESRD-T0 patients compared to controls, the only exception being CD19+CD5+ cells. Apoptotic changes were prominent in ESRD-T0 patients and were exacerbated by HD.