Cathepsin B-deficient mice as source of monoclonal anti-cathepsin B antibodies.

Cathepsin B has been demonstrated to be involved in several proteolytic processes that support tumor progression and metastasis and neurodegeneration. To further clarify its role, defined monoclonal antibodies are needed. As the primary structure of human cathepsin B is almost identical to that of the mouse, cathepsin B-deficient mice were used in a novel approach for generating such antibodies, providing the chance of an increased immune response to the antigen, human cathepsin B. Thirty clones were found to produce cathepsin B-specific antibodies. Seven of these antibodies were used to detect cathepsin B in MCF10-DCIS human breast cancer cells by immunocytochemistry and immunoblotting. Five different binding sites were identified by epitope mapping giving the opportunity to combine these antibodies in oligoclonal antibody mixtures for an improved detection of cathepsin B.