Short- and long-term effects of hemodialysis on platelet and monocyte activity markers of atherosclerosis in patients with end-stage renal disease

Background: In hemodialysis (HD) patients cardiovascular events represent the predominant cause of mortality. Since platelet and monocyte activity markers play an important role in cardiovascular mortality, this study assessed the influence of HD on these markers. Methods: Forty one HD patients (25 male, 16 female) were included. Blood samples were obtained before and after a single HD session at baseline and again after an elapsed period of 114 ± 21 days (91–175 days) on maintenance hemodialysis. Surface expression of CD40L and CD62P on platelets, tissue factor binding on monocytes and platelet-monocyte aggregates were measured by flow cytometry. Plasma levels of monocyte chemotactic protein-1 (MCP-1), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFa) and soluble CD40L were analyzed by enzyme linked immunosorbent assay. Results: Tissue factor on monocytes was significantly increased after a single HD session at baseline (p = 0.041), whereas platelet-monocyte aggregates, the expression of CD40L and CD62P on platelets did not change significantly. After a mean of 114 ± 21 days of HD therapy, tissue factor on monocytes (p < 0.0001), platelet-monocytes aggregates (p < 0.0001), plasma levels of MCP-1 (p = 0.012) and TNFa (p = 0.046) were significantly decreased compared to baseline values. In contrast, platelet surface expression of CD40L and CD62P as well as plasma levels of sCD40L and IL-6 were not attenuated significantly. There was no significant correlation detected between the markers examined and the cumulative time on hemodialysis. Conclusions: Platelet and monocyte activity markers assessed in this study do not appear to be significantly increased by HD therapy. Therefore, these markers probably cannot be accountable for increased cardiovascular mortality in chronic HD patients.