Production of monoclonal antibodies recognizing cancer-associated antigens expressed on mucin-type sugar chains

To obtain monoclonal antibodies directed to mucin-type sugar chains, mice were immunized with bovine submaxillary mucin (BSM) that had been conjugated with ovalbumin. Conjugation of BSM with ovalbumin enhanced the antigenicity of BSM to about five to ten times that of intact BSM and resulted in the establishment of ten hybridomas, all of which secreted monoclonal antibodies toward BSM. Most of the antibodies secreted by these hybridomas did not react with glycolipids but did react with glycoproteins. Several antibodies lost their reactivity when sialic acid residues were removed from BSM, indicating that these antibodies recognize carbohydrate moieties of mucins. Immunohistochemical studies revealed that three of the antibodies recognized human ovarian cancer-associated carbohydrate antigens. In addition, one of these three antibodies reacted with a human cultured colonic cancer cell line. The protocol described in this paper was effective in producing monoclonal antibodies that recognize mucin-carbohydrates and some of the generated antibodies can be applied to the detection of cancers.