Diminished expression of placental isoferritin p43 component in first trimester abnormal pregnancies.

Human placental isoferritin (PLF) is a sub-type of human ferritin mainly composed of a 43 kD protein, which has an immunosuppressive activity and may be involved in the downregulation of the maternal immune system during pregnancy. The aim of this study was to evaluate the distribution of p43 in the placental tissue of abnormal first trimester pregnancies. Samples of villous and decidual tissues were collected between 7 and 12 weeks' gestation from 28 missed abortions and eight complete moles. Samples of placental tissue from 20 normal pregnancies of similar gestational age were used as controls. The localization of p43 was determined by immunohistochemical techniques using CM-H9 monoclonal antibody. Compared to controls, specific p43 immunoreactivity was low in the villous syncytiotrophoblast of missed abortions and absent from all villous cellular types in complete moles. These findings correlate well with the low level of maternal serum PLF found previously in early pregnancy failures and molar gestation. This suggests that PLF may be involved in the pathogenesis of early pregnancy disorders related to an abnormal placentation.