Human cytotrophoblastic antigens defined by monoclonal antibodies

Monoclonal antibodies have been raised against cytotrophoblast. Two different antigens, defined on cytotrophoblast but not on syncytiotrophoblast were designated ACT-1 and ACT-2, respectively. Chorionic villi were taken from normal early pregnancy and processed for immunization by two different procedures. ACT-1 was demonstrated to be present in lung alveolar cells, endothelial mucosa of the jejunum, colon, ureter, urinary bladder and the fallopian tube, and endometrial gland of the pregnant uterus. On the other hand, ACT-2 was present in the endothelial mucosa of the stomach, endothelium of the renal vessel, and the decidua of the pregnant uterus. Although the monoclonal antibodies did not react with such established cell lines as Bewo, SCH, OVK-18, HHUA, MK-01, FL, BHK and P3 X 63Ag 8 . 653, they did react with some of the cell lines when the cell membrane was destroyed with Triton X-100. Each antibody, therefore, may recognize the antigen not on the cell membrane but in the cytoplasm. The antigens might be shed or may disappear in the process of differentiation from cytotrophoblast to syncytiotrophoblast.