monospecific antibodies are produced which are specific for fragments of the connective tissue protein aggrecan , generated by specific stromelysin cleavage . these monospecific antibodies are used in an assay system to detect polypeptide fragments of aggrecan , produced by the specific cleavage of aggrecan by stromelysin . the presence of aggrecan polypeptide fragments demonstrates stromelysin activity . elevations of stromelysin occur in osteoarthritis , rheumatoid arthritis , atherosclerotic lesions , gout , inflammatory bowel disease , idiopathic pulmonary fibrosis , certain cancers , joint injuries , and numerous inflammatory diseases . the monospecific antibodies and the assay system are used to quantitate aggrecan polypeptide fragments as a readout of stromelysin activity and to evaluate potential stromelysin inhibitors .