AUTOLOGOUS HUMAN B-CELL IMMUNE-RESPONSE TO PULMONARY ADENOCARCINOMATOUS POLYMORPHIC EPITHELIAL MUCIN

In order to investigate whether a B-cell immune response to the polymo rphic epithelial mucin (PEM) is present in adenocarcinomatous patients , peripheral blood lymphocytes from 20 patients with adenocarcinomas f rom various sites were fused with the mouse-human heteromyeloma cell l ine SHM-D33. One IgM(K) monoclonal antibody derived from peripheral bl ood lymphocytes of a patient with a lung adenocarcinoma was generated with binding reactivity for bovine submaxillary mucin (BSM). The latte r is one of the PEMs, and it contains a large amount of the tumor-asso ciated sialosyl-Tn epitope. The generated antibody was designated KMD- 2. Immunohistological studies on various tissues showed that KMD-2 rea cted with 6/6 colorectal adenocarcinomas and 4/6 pulmonary adenocarcin omas. The antibody also displayed a slight degree of cross-reactivity with a limited number of normal tissues, especially those that elabora te mucin. Our data show that an autologous antibody response in the fo rm of IgM to the immunosuppressive PEM is present in some adenocarcino matous patients. The data also suggest that the KMD-2 (IgM/K) antibody may be of clinical importance for diagnostic purposes of adenocarcino matous disease.