Effect of different dialyzers on proteinases and proteinase inhibitors during hemodialysis

The effect of different membrane materials on plasma levels of granulocyte elastase, 'unspecific' proteolytic (azocasein-hydrolyzing) activity, and activity and concentration of the main plasma proteinase inhibitors alpha 1-proteinase inhibitor (alpha 1PI) and alpha 2-macroglobulin during hemodialysis was investigated. Cuprophan (679.6 +/- 80.0 ng/ml) and polymethyl methacrylate (873.0 +/- 20.6 ng/ml) membranes caused a significantly higher maximal increase of plasma levels of granulocyte elastase-alpha 1-proteinase inhibitor (E-alpha 1PI) complex compared with polyacrylonitrile (395.3 +/- 56.0 ng/ml) or polysulfone (295.2 +/- 41.3 ng/ml) membranes (healthy subject 70.3 +/- 4.4 ng/ml). The activity of alpha 1PI increased significantly during hemodialysis using polyacrylonitrile (+36%) or polysulfone (+29%) membranes, whereas this increase was less using cuprophan (+6%) or polymethyl methacrylate (+8%) membranes. The reverse effect, however, was observed analyzing alpha 1PI concentrations (cuprophan +33%, polymethyl methacrylate +23%, polyacrylonitrile +12%, polysulfone +7%). 'Unspecific' proteolytic activity and non-trichloroacetic acid-precipitable small molecular weight plasma protein fraction decreased significantly during hemodialysis in the presence of all four membranes. We conclude that neutral granulocyte proteinases can be released during hemodialysis independent of the change of white blood cells during the 1st h of dialysis therapy.