Production, characterization and use of monoclonal antibodies against the major extracellular human cysteine proteinase inhibitors cystatin C and kininogen

Murine monoclonal antibodies against the major cysteine proteinase inhibitors of human biological fluids, cystatin C and kininogen, were produced. The cystatin C antibody, HCC3, with a Ka of 2times107 l/mol, increased the inhibition of papain by cystatin C and was suitable for use in immunoblotting, immunohistochemistry and in the construction of a sensitive sandwich enzyme immunoassay for quantification of cystatin C. It recognized not only free cystatin C but also cystatin C in complexes with cysteine proteinases. The kininogen antibody, HK4, was directed against the third, cysteine proteinase inhibitory domain of the heavy chain of kininogen (Ka=1times107 l/mol), but did not influence the papain inhibitory activity of kininogen. It reacted with free kininogen as well as kininogen in complex with cysteine proteinases. Both antibodies could be used for the production of specific immunosorbents.