Response of complement and neutrophils to hydrophilized synthetic membranes

Membranes prepared from hydrophobic synthetic polymers adsorb proteins. Alloying these polymers with hydrophilic polymers increases water wetability and reduces hydrophobic interactions. The authors tested the hypothesis that alloying could affect the biocompatibility of the resultant membrane. Polymer films were cast from solutions containing 12% polysulfone and 4, 8, or 12% polyvinylpyrrolidone in dimethylacetamide. The effect of the films on the complement system and neutrophil function was assessed by incubating them in normal plasma and whole blood at 37 degrees C. Complement activation was followed by measuring plasma concentrations of C3a des Arg and C5a des Arg. Flow cytometric measurements of phagocytic capacity, H2O2 production, and expression of the C3bi receptor were used to assess neutrophil function. The degree of complement activation was found to depend on the composition of the polymer film. C3a des Arg and C5a des Arg generation decreased 75% and 86%, respectively, as the polyvinylpyrolidone content of the casting solution was increased from 25 to 50%. This was accompanied by a decrease in stimulation of neutrophil H2O2 production and C3bi receptor expression. From these data, the authors conclude that alloying with polyvinylpyrrolidone can affect the biocompatibility of polysulfone.