Detection of a metalloproteinase in patients with acute and chronic renal failure

The effect of different dialyzer membrane materials (cuprophan, cellulose hydrate, polyacrylonitrile, polymethylmethacrylate, ethylene-vinyl alcohol copolymer) on the ultrafiltrate proteinase activity was investigated in 26 patients with acute renal failure (ARF) and 40 patients undergoing regular hemodialysis treatment (RDT). Furthermore, the proteinase activity was characterized in vitro using azocasein and phosphorylase kinase as substrates in the absence and presence of different proteinase inhibitors. Proteinase activity of ultrafiltrates obtained from ARF patients was significantly enhanced with the dialyzer KF 101 (ethylene-vinyl alcohol copolymer). The digestion pattern of phosphorylase kinase revealed an identical type of proteinases in ultrafiltrates of ARF and RDT patients. The pH optimum of this proteinase was at alkaline pH. The proteinase activity could be inhibited in the presence of EDTA, whereas serine proteinase inhibitors were ineffective. Furthermore, the inactivated proteinase after Sephadex G-10 chromatography (in order to separate ultrafiltrate electrolytes and trace elements from protein) could be reactivated after the addition of Mg++ and/or Ca++. We conclude that a metalloproteinase can be found in ARF and RDT patients, and that KF 101 is more effectively eliminating the proteinase activity in ARF patients than other dialyzer membranes.