The modulating effect of human chorionic gonadotropin on lymphocyte blastogenesis.

Human chorionic gonadotropin (HCG) produced by fetal trophoblastic cells was suggested to play a role in the suppression of maternal lymphocyte response against the fetal allograft. Reports supporting this concept have demonstrated a suppressive effect of crude HCG on lymphocyte blastogenesis. However, similar doses of purified hormone preparations were unable to inhibit lymphocyte stimulation with mitogens. A modulating influence of phenol-free and immunoglobulin-free HCG preparation on lymphocyte blastogenesis is presented. Enhanced lymphocyte stimulation with various mitogens occurred in cultures supplemented with HCG at low doses. On the other hand, higher hormone concentration exerted an inhibitory effect on lymphocyte blastogenesis. An increase in lymphoid cell concentrations was demonostrated in cultures supplemented with the hormone preparation. These observations are compatible with the suggested role of HCG in the maternal tolerance toward a histoincompatible fetus.