Activated and Regulatory T Lymphocyte Populations in Chronic Hemodialysis Patients

T lymphocyte activation after leukocyte membrane interaction may play a role in immune dysfunction associated with hemodialysis (HD). Studies of T-lymphocyte activation markers in HD have yielded conflicting results, perhaps due to the use of a limited number of markers and different measurement techniques. We studied the lymphocyte activation markers CD25 (interleukin-2 receptor), CD38, CDw49b (VLA-2), CD71 (transferrin receptor), and HLA-DR, as well as the surface antigens CD3, CD4, CD7, and CD8 by two-color flow cytometry in 23 chronic HD patients before and after a single dialysis session; we also studied 30 normal controls. There was no increase in the percentage of activated T cells in the controls and in the patients pre- and post-HD. Conversely, the percentage of CD3+/CD71 + (transferrin receptor) cells was significantly decreased in the patients pre-HD compared with the controls (3.6% ± 0.5% [mean + SEM] v 5.9% ± 0.5%; P < 0.005). A single dialysis session did not alter the percentage of activated subsets, but led to significant depletion in the number (×10⁹/L) of cells that were CD3+ (1.10 ± 0.10 v 0.97 ± 0.09; P < 0.05), CD7+ (1.0 ± 0.09 v 0.85 ± 0.08; P < 0.0001), and CD8+ (0.50 ± 0.06 v 0.37 ± 0.04; P < 0.001), but not CD4+ cells (0.73 ± 0.08 v 0.69 ± 0.07; P = NS). These data indicate that the chronic HD patients at baseline “predialysis” do not appear to have an increased percentage of circulating activated T lymphocyte subsets and that the CD3+/ CD71+ subset is in fact decreased. Moreover, a single dialysis session results in depletion of select lymphocyte subsets, including CD7 and CD8, which may play a role in the immunologic dysfunction in HD patients.