Effects of dialysis membrane nature on intradialytic phagocytizing activity

Blood-membrane contact in the extracorporeal circuit affects the activation of many biological systems. Among these, phagocytizing activity has been reported to be influenced by the nature of the hemodialysis membrane used, whether cellulosic or synthetic. This work reports on an ex-vivo, comparative test between cellulosics and synthetics concerning the effects of blood-membrane contact on the polymorphonucleate and monocyte phagocytizing function, both during and after the hemodialysis session. By means of flow cytometry, we evaluated the capacity for phagosoma formation and oxidative burst both in polymorphonucleates and monocytes. Ten hemodialysis patients were included in the study. Six separate dialysis procedures for each patient were considered, one per dialyzer (3 cellulosic and 3 synthetic membranes). Tests were performed at 15', 60' 210' and 4 hours after the session end. Comparative evaluation was made according to Student's t test. Polymorphonucleate phagocytosis and oxidative burst activation were globally more marked for synthetic than cellulosic membranes, tending to level out in the post-dialysis. This result could be affected by their functional exhaustion following pulmonary sequestration. Monocyte intradialytic phagocytosis and oxidative burst proved more activated by cellulosic membrane. All differences tended to vanish in the post-dialysis.