Evidence for a Variant of Gonadotropin in Choriocarcinoma.

Intraperitoneal injection of human chorionic gonadotropin in the rat induces a dose-dependent frequency of ovarian hyperemia. The occurrence of such hyperemia can be inhibited by pre-injection (3 hours) of antisera from rabbits immunized with gonadotropin extracts. It is demonstrated that the retained capacity of gonadotropin to induce hyperemia following antisera injections is greater when the gonadotropin is from patients with choriocarcinoma than when the gonadotropin is from pregnant women or U.S.P. standard human chorionic gonadotropin. This differential shows up consistently for pools of urinary extracts and for extracts from individual patients with choriocarcinoma prior to therapy and does not seem to be related to the source of gonadotropin used for rabbit immunization. The data are interpreted as indicating that there is a variant of chorionic gonadotropin in the urine of choriocarcinoma pa tients. Further work would be necessary before the present findings could be employed usefully in the detection of choriocarcinoma.