Production and characterization of murine monoclonal antibody to human alpha-lactalbumin.

Human alpha-lactalbumin (alpha-LA), a milk protein normally produced by, and restricted to, functionally differentiated breast epithelial cells has been shown immunohistochemically to be a good marker for breast cancer. Antibodies with specificity only for human alpha-LA have not previously been reported. The present study documents the production and characterization of an IgG1 murine monoclonal antibody with specificity restricted only to human alpha-LA. This monoclonal antibody, designated ET-1, was purified by affinity chromatography using human alpha-LA. Specificity of ET-1 for human alpha-LA was established by enzyme linked immunosorbent assay (ELISA), absorption studies, immunoprecipitation and by immunoblotting. ET-1 binds to human alpha-LA with a KD of 7.41 x 10(-8) mol/l and does not cross-react with bovine alpha-LA. This unique reactivity of ET-1, which is not inherently shared by polyclonal antisera, should enable the antibody to be used for the development of a sensitive immunoassay for circulating human alpha-LA.