Monoclonal antibodies to human syncytiotrophoblast

Two monoclonal antibodies, NDOG1 and NDOG2, have been produced which are directed towards human syncytiotrophoblast. The antigens detected by these antibodies are absent from human liver, heart, kidney, brain and from normal human sera. The NDOG1 antigen but not NDOG2 antigen is a component of pregnancy sera and falls to undetectable levels within 6 hours of placental delivery. This molecule is not human chorionic gonadotrophin, human placental lactogen, placental alkaline phosphatase. SP1 or PAPP-A. Immunoperoxidase staining shows that both antigens are on apical aspects of the syncytiotrophoblast and not in the villous stroma.