Suppression of antitumor lymphocyte mediated cytotoxicity by human chorionic gonadotropins

The effect of human chorionic gonadotropin on the in vitro cytotoxicity of lymphocytes against human transitional cell carcinoma cells was studied in 9 patients using the microcytotoxicity assay. Lymphocytes from 6 patients were cytotoxic against transitional cell carcinoma cells. However, in the presence of human chorionic gonadotropin the cytotoxicity of these lymphocytes against transitional carcinoma cells was diminished. Human chorionic gonadotropin alone or in combination with non-cytotoxic lymphocytes did not change the growth of target cells and human chorionic gonadotropin did not have a direct toxic effect on lymphocytes alone. These results demonstrate that human chorionic gonadotropin can inhibit the cytotoxic action of lymphocytes against human tumor cells in vitro. Human chorionic gonadotropin may contribute to the poor prognosis associated with certain human chorionic gonadotropin-secreting human tumors.