IDENTIFICATION OF PROTEINASE-3 AS THE MAJOR CASEINOLYTIC ACTIVITY IN ACUTE HUMAN WOUND FLUID

Wound fluid contains several proteinases that are important in the rep air process. In this study, we analyzed caseinolytic activity in wound fluid obtained from acute (burn) wounds. Caseinolytic activity in wou nd fluid increased, markedly 2 d after injury and appeared on casein z ymographs as a series of bands or a smear ranging from 30 to 100 kDa. Most of the enzyme activity was inhibited by the Synthetic human neutr ophil elastase inhibitor MDL 27,367 but not by the naturally occurring inhibitor of elastase, human secretory leukoproteinase inhibitor. Fra ctionation of wound fluid indicated that a single enzyme accounted for approximate to 80% of the caseinolytic activity. This enzyme degraded the elastase substrate methoxysuccinyl-ala-ala-pro-val-p-nitroanilide at a slow rate. The above findings suggested that the enzyme responsi ble for caseinolytic activity might be proteinase 3, an elastase-relat ed enzyme whose physiologic functions are poorly understood. Consisten t with the above possibility, we found that monoclonal antibodies agai nst proteinase 3 removed caseinolytic activity from wound fluid, and t hat purified proteinase 3 had a similar caseinolytic profile and inhib itor sensitivity to burn fluid.