Immunosuppressive activity of human chorionic gonadotrophin preparations in vivo: evidence for gonadal dependence

Human chorionic gonadotrophin preparations (hCG), when injected ip daily for 4 days, suppress the delayed-type hypersensitivity (DTH) response of mice to sheep red blood cells. Preparations of crude hCG, purified hCG subunits, and hCG that was formed by recombining the purified subunits showed immunosuppressive activity in accord with their gonadotrophic activity. The immunosuppressive effects in male and female mice were comparable. However, removal of the gonads completely abrogated the immunosuppressive activity of hCG in both males and females, suggesting that the effect of hCG is mediated by a factor released from the gonads. We conclude that the hCG molecule itself exhibits immunosuppressive activity in vivo in both male and female mice and that the gonads are required for the expression of this activity.