Human chorionic gonadotropin in human neoplastic cells.

Peroxidase-labeled antibody against the beta chain of human chorionic gonadotropin was used to demonstrate that 25 human malignant tumors contained this antigen. The antigen was localized both in the cytoplasm and on the surface of the malignant cells. Human chorionic gonadotropin may be responsible for both selective maternal immuno-suppression by fetal tissue and host immunosuppression by tumors.