Human chorionic gonadotropin in human placentas from normal and preeclamptic pregnancies

The aim of this study was to examine the distribution of human chorionic gonadotropin (hCG) in the human placenta of normotensive and preeclamptic pregnancies and to determine by computer image analysis, whether differences in hCG immunoreactivity occurred in preeclamptic as apposed to normotensive pregnancies. We discuss how far elevated maternal serum levels of hCG normally observed in preeclamptic patients reflect an increased secretory activity of the syncytiotrophoblast.

We used the immunoperoxidase technique to locate hCG. Quantification of immunostaining intensity was done by computer image analysis.

In normotensive placentas from all the gestational ages human chorionic gonadotrophin immunoreactivity was specifically detected in the syncytiotrophoblast. There is an apparent decrease in the intensity of the hCG immunostaining in the syncytiotrophoblast from the 29th to 36th week of gestation in normotensive placentas. No hCG immunostaining was observed in the villous or extravillous cytotrophoblast of all placentas. In preeclamptic placentas the expression of hCG was homogeneous with a moderate to intense immunoreactivity in the syncytiotrophoblast. Microdensitometric analysis of the section from normotensive and preeclamptic placentas indicated that there is a statistically significant preeclampsia-induced increase in immunohistochemical reaction intensity for hCG (p < 0.05).

This study seems to demonstrate that increased production of hCG by preeclamptic placentas is associated with strong hCG immunostaining of the syncytiotrophoblast.