A MONOCLONAL-ANTIBODY CF703 RAISED AGAINST HUMAN FETAL LUNG RECOGNIZES A NOVEL ONCO-FETAL MUCIN

To obtain murine monoclonal antibodies (MAb), mice were immunized with the extract of a human fetal lung from the first trimester of gestati on as initial immunogen followed by booster immunization with a human lung cancer cell line. MAb CF703 which reacted to the booster material was screened and selected. In adults, expression of the antigen defin ed by MAb CF703, CF703 antigen, was shown immunohistochemically in 78% of gastric carcinomas (14/18), 59% of ovarian adenocarcinomas (10/17) , 50% of pancreatic carcinomas (5/10), 17% of lung carcinomas (4/24), 50% of uterine cervical adenocarcinomas (2/4), 20% of endometrial aden ocarcinomas (1/5) and 10% of renal cell carcinomas (1/10). Other malig nant tumors failed to demonstrate the reactivity. MAb CF703 was weakly reactive with only three adult normal tissues including surface linin g of gastric mucosa, Brunner's glandular epithelia of the duodenum and columnar epithelia in the uterine endocervix. In fetal tissues, 5 of 23 tissues including squamous epithelia in lower portion of the;esopha gus, surface epithelia of gastric mucosae and goblet cells in the smal l and large intestine were reactive. The CF703 antigen had a molecular weight over 500 kDa and its epitope was carbohydrate in nature by rea son of the resistance to proteinase digestion and sensitivity to perio date oxidation, neuraminidase and alkaline-borohydrite. MAb CF703 reco gnizes probably a unique epitope in oncodevelopmental mucin glycoprote in. Additionally, this immunization method has the advantage of rapid acquirement of MAbs with restricted, narrow cancer spectrum and is a w orthy strategy for generating the new MAbs.