Protease removal by means of antiproteases immobilized on supports to be used for hemodialysis or extracorporeal blood circulation-dependence on reciprocal amounts of proteases and antiproteases.

This work studies protease concentration decrease in aqueous solutions in contact with a modified polyethersulphone graft membrane onto which antiproteases were immobilized. As a model of protease/antiprotease interaction, elastase and a1-antitrypsin were used. Experiments were carried out either under fixed amounts of immobilized antiproteases and variable protease concentration or under fixed protease concentration and variable amounts of immobilized antiproteases. In both cases, active protease concentrations decreased with increase in contact time with the membrane. Experimental conditions under which active elastase concentration becomes zero were also found. Occurrence of the same phenomenology has also been ascertained with protease solutions obtained from human blood neutrophyls. The membrane activated with a1-antitrypsin showed differential inhibitory power on elastase and cathepsin G. This technology allows construction of the most appropriate membranes to be used in hemodialysis and extracorporeal circulation when elastase is released.