Production of monoclonal antibodies for the immunohistochemical detection of gastric carcinomas.

About 700 antibody-secreting hybrids were obtained by fusion of lymphocytes, (harvested from mice hyperimmunized with the human gastric carcinoma line KATO III) and P3-X63-Ag8-653 myeloma cells. Antibody specificity was screened in ELISA performed on glutaraldehyde-fixed cultured cells and on paraffin-embedded tissue sections stained with the method of avidin-biotin-peroxidase. When tested in ELISA, the monoclonal antibody produced by the hybrid clone BD-5 was found to bind only to the cell line used as immunogen, among the many neoplastic or normal human cell lines tested. When assayed on paraffin sections with the avidin-biotin-peroxidase method, the BD-5 monoclonal antibody stained gastric carcinomas, but not the normal mucosa. Pancreatic carcinomas were also stained, while the corresponding normal gland was not. The antibody strongly stained the normal colonic and small intestinal mucosa. Among the other normal or neoplastic tissues tested, a weak reactivity was observed only with some epithelial cells of the salivary glands and with some carcinoma cells of the uterus and of the lung. It is concluded that the BD-5 antibody reacts with an epitope normally present on intestinal mucosa, which, following neoplastic transformation, is ectopically expressed also on gastric and pancreatic carcinomas. This monoclonal could represent a useful reagent for histopathological diagnosis.