Direct interaction between polymorphonuclear neutrophils and cuprophan membranes in a plasma-free model of dialysis

Plasma-free, purified, normal, human polymorphonuclear neutrophils (PMN) were recirculated for 60 minutes in an experimental model of dialysis using cuprophan membranes and acetate or bicarbonate dialysate. At different time intervals, the intracellular contents of PMN-derived cationic proteins (NCP), the release of lysosyme, beta-glucuronidase and PAF as well as the occurrence of PMN and platelet aggregating activities in the supernatants were evaluated. The formation of PMN aggregates, the depletion of intracellular contents of NCP together with the release of lysosomal constituents occurred early (5-10 min) in the course of recirculation. These events were concomitant with the occurrence of PMN aggregating activity in the supernatants due to the release of NCP, as it was antagonised (30-40%) by a rabbit anti-human NCP, and to the release of PAF which also accounted for the platelet aggregating activity that was independent from both adenosine diphosphate and cyclo-oxygenase inhibitors. These data suggest that direct interaction occurs between human PMN and cuprophan in in vitro conditions in the absence of plasma factors and point to a role for cellular mediators in the pathogenesis of the intravascular alterations occurring early in haemodialysis.