Comparative determination of the antiproteolytic potential of therapeutically used blood protein preparations

Clinical situations with release of proteinases from blood cells or tissues into the circulation may result in a marked decrease of blood proteinase i nhibitor content which in turn may result in a capillary leak syndrome, sho ck and even in exitus letalis. Replenishment of blood proteinase inhibitors is of benefit in such situations. In this study the inhibitory potential o f fresh plasma, fresh frozen plasma and the liquid plasma protein preparati on Biseko has been tested with the following enzymes: human leukocyte elast ase, human plasmin, human matrix metalloproteinase-9, bovine trypsin, bovin e chymotrypsin and rat liver lysosomal cathepsins. The concentration of the blood protein preparations resulting in 50% inhibition of constant amounts of each of the enzymes has been determined by plotting residual activity v s, log of concentration of blood protein preparation in enzyme assays. From these IC,, values inactivation ratios for 1 mg and 1 mi of the blood prote in preparations was calculated. These inactivation ratios show an equal sui tability of fresh plasma, fresh frozen plasma or full plasma proteins for r eplenishment of plasma proteinase inhibitory potential in vitro. As additio nal finding, commercial preparations of human serum albumin exert a surpris ingly high inhibitory potential to lysosomal cathepsins.