PLATELET-LEUKOCYTE AGGREGATION DURING HEMODIALYSIS

Platelet-leukocyte aggregation during hemodialysis. Hemodialysis is as sociated with simultaneous changes in leukocytes and platelets, but it is unclear whether these alterations affect the interactions between these cell types. To evaluate this process, we examined the appearance of platelet specific antigens (CD41) on leukocytes as an index of pla telet-leukocyte aggregation during hemodialysis using three different synthetic membranes. Patients with end-stage renal disease (ESRD) on l ong-term hemodialysis treatment were enrolled. Flow cytometric techniq ues and platelet specific monoclonal antibodies (MoAb) that recognize the glycoprotein complex on resting and activated platelets (anti-CD41 ), the activated GPIIb-IIIa complex receptor (anti-LIBS1), and the p s electin GMP140, that is exposed on platelet plasma membrane after acti vation and platelet degranulation (anti-CD62), were used. Subjects wit h ESRD had a lower predialysis platelet surface expression of CD41 and LIBS1 compared to normal controls, but unchanged CD62 expression. In parallel, patients with ESRD manifested a uniformly reduced platelet-l eukocyte microaggregates predialysis compared to normal controls. When examined across the dialyzer, however, an increase in platelet-neutro phil and platelet-monocyte microaggregates was observed with all three synthetic membranes at both 15 and 30 minutes after initiation of dia lysis. This phenomenon could be duplicated in vitro by physiologic con centrations of the platelet specific agonist ADP, but not by the compl ement factors C3a or C5a. We conclude that platelet-leukocyte aggregat es occur during dialysis likely related to a primary platelet activati on mechanism. This phenomenon may serve as a new biocompatibility para meter and may shed light on some of the biologic consequences of hemod ialysis.