Complement activation during hemodialysis: clinical observations, proposed mechanisms, and theoretical implications

Human C3a radioimmunoassay techniques were employed to define both the temporal profile and the amount of complement activation taking place in the extracorporeal circuit during maintenance hemodialysis. Prospective studies demonstrated that C3a formation, like hemodialysis-associated leukopenia, was a transient phenomenon that occurred predominantly during the first 30 min of dialysis. Quantitative comparisons revealed that new Cuprophan hemodialyzers displayed somewhat greater complement-activating potential than cellulose acetate dialyzers. By contrast to new Cuprophan membranes, both reused Cuprophan and polyacrylonitrile dialyzers exhibited only a modest ability to activate human complement. These findings are compatible with the known mechanisms of complement activation and suggest that certain chemical and biochemical methods might be exploited to enhance the biocompatibility of cellulose dialysis membranes.