A human monoclonal antibody to carbohydrate moiety of carcinoembryonic antigen

Hybridoma BSRF-S-97, secreting a human monoclonal antibody of IgG1 subclass reactive to the carcinoembryonic antigen, was generated by fusing the regional lymph node lymphocytes from a cervical cancer patient with RF-S1 human–mouse heteromyeloma fusion line. This monoclonal antibody was found specifically reactive to carinoembryonic antigen-producing cell lines, including those of cervical cancer (SKG-II), mucinous type ovarian cancer (RMUG-L), stomach cancer (MKN-45), and lung cancer (PC-10). The monoclonal antibody reactivity with pepsin- and periodate-treated carcinoembryonic antigen demonstrated that this monoclonal antibody recognizes the carbohydrate moiety of carcinoembryonic antigen specifically. Possibilities of the monoclonal antibody reaction with mucin and blood-group antigens were excluded by the comparative studies with a placental mucin-containing protein which reacted with carcinoembryonic antigen-specific rabbit polyclonal antibody. The monoclonal antibody conjugated with Pseudomonas exotoxin showed potent regression effects on the growth of the MKN-45 cell line in both the dish culture and xenografted nude mice, indicating potential usefulness of this human monoclonal antibody as a promising tumor targeting vehicle.