DEFINITION OF 3 SPECIES-SPECIFIC MONOCLONAL-ANTIBODIES RECOGNIZING ANTIGENIC STRUCTURES PRESENT ON HUMAN EMBRYONAL CARCINOMA-CELLS WHICH UNDERGO MODULATION DURING INVITRO DIFFERENTIATION

Three novel species-specific monoclonal antibodies 5.1.H, 8.7.D and 13.7.A raised against semi-purified detergent solubilized fractions of the Tera I embryonal carcinoma (EC) cell line are restricted in their in vitro distribution to undifferentiated human EC cell lines. Competition experiments have established that distinct antigenic specificities are seen by the 3 different monoclonal antibodies. All 3 antigens 5.1.H, 8.7.D and 13.7.A, defined by these monoclonal antibodies, undergo developmental regulation and cease to be expressed on Tera 2 clones 5 and 12 after retinoic-acid-induced differentiation and on LICR LON HT 39/7 cells after phorbol-ester-induced differentiation. These results taken together with the extremely limited in vivo tissue distribution of the defined antigens suggest that the 5.1.H, 8.7.D and 13.7.A monoclonal antibodies define distinct oncofetal antigens.