A MONOCLONAL ANTIBODY TO A TESTICULAR CHORIOCARCINOMA CELL LINE

Abstract

Monoclonal antibodies were developed in order to define tumor-associated antigens or differentiation antigens of human testicular choriocarcinoma by fusing SP2/0-Ag14 mouse myeloma with splenocytes from BALB/c mice immunized with testicular choriocarcinoma cell line JHTK-1. Solid-phase enzyme immunoassay (EIA) using glutaraldehyde-fixed cultured cell lines as targets was carried out for antibody screening. After cloning a selected hybridoma culture, we succeeded in isolating a monoclonal antibody (Cho. 1) which recognized an antigen expressed predominantly in choriocarcinoma cell lines. By quantitative absorption assay, Cho. 1 bound with normal chorion and testicular choriocarcinoma tissues, i. e., normal and malignant trophoblastic tissues, but not with normal testis, seminoma, embryonal carcinoma or yolk sac tumor tissues. By solid-phase radioimmunoassay (RIA), Cho. 1 did not bind with well-known marker antigens such as human chorionic gonadotropin (HCG), pregnancy specific β₁-glycoprotein (SP1) or α-fetoptotein (AFP). In conclusion, we believe that Cho. 1 recognizes a trophoblast-specific antigen that is different from placental antigens such as HCG and SP1. Cho. 1 may be useful clinically as a new agent for the diagnosis and treatment of testicular choriocarcinoma.