Effects of crude and purified human chorionic gonadotropin on lymphocyte response

Human chorionic gonadotropin (hCG) preparations with different biological activities were tested for their inhibitory effects on mitogenic of allogenic induced lymphocyte response. Various crude hormone batches inhibited the lymphocyte reaction in a dose-dependent manner. However, we found a varying suppression of lymphocyte response not correlated to the biological activity (2,660-4,300 IU/mg) of crude hormone. Fractions with very low gonadotropic activity (much less than 500 IU/mg) showed a 100-fold inhibition of lymphocyte reaction. Conversely, the enrichment of highly purified hCG with strong biological activity (greater than 10,000 IU/mg) had no inhibitory effect on mitogenic or allogenic induced lymphocyte transformation. Isoelectrofocussing and immunoelectrophoretic investigations indicated that the inhibition is probably caused by nondialyzable sialoglycoproteins. It is therefore very doubtful whether hCG plays an important part in maternal tolerance of the fetal allograft.