ANTIPROTEASE ACTIVITY IN URINE OF PATIENTS WITH INFLAMMATORY SKIN DISORDERS

Polymorphonuclear leukocytes contain well-defined proteolytic enzymes in their azurophilic granules that can be released into tissues during inflammation, producing a localized excess of proteases that causes a protease-antiprotease imbalance with subsequent tissue destruction. T he antiproteolytic compounds of the epidermis, such as the protease in hibitors elafin and antileukoprotease, are thought to counteract the p roteolytic tissue damage. We investigated the urine of patients suffer ing from inflammatory skin conditions (e.g., erysipelas, psoriasis) fo r the presence of urinary antiprotease activities. Purification of ela stase-inhibitory activities from pooled urine samples by cation exchan ge high-performance liquid chromatography and preparative and analytic al reverse-phase high-performance liquid chromatography yielded two di fferent types of inhibitors. One was a cationic, acid-stable, and elas tase-specific inhibitor of M(r) 6,000 by size-exclusion high-performan ce liquid chromatography. N-terminal amino acid sequence analysis of t he first 28 residues showed identity with elafin, an elastase-specific inhibitor recently isolated from psoriatic scales. The second antipro tease activity was due to two forms of urinary bikunin, the inhibitory subunit of inter-cy-inhibitor. Both bikunin fragments, with M(r) 4,00 0 and 16,000, were identified by N-terminal amino acid sequence analys is of the first 10 residues and were characterized by an antiproteolyt ic profile against human leukocyte elastase, cathepsin G, and trypsin. Urinary protease inhibitors may serve as diagnostic markers of inflam matory diseases.