Regulation of complement activity via the alternative pathway in placentas of mouse spontaneous abortions.

Placental complement has the potential to induce autologous embryo injury. We have previously found a significant elevation of adipsin, an activating factor of the alternative complement pathway, in mouse placentas from spontaneous abortions. The present study was aimed to evaluate regulation of the alternative complement pathway in placentas of mouse spontaneous abortions. Protein was purified from mouse placentas at normal and abortion implantation sites on day 14.5 of pregnancy. The activity of the alternative complement pathway was slightly intensified following addition of protein from abortion placentas. Western blotting revealed that Crry was clearly present in the placentas from abortions. Thus, the complement regulating system through Crry is functional to restrict alternative complement activity in abortion placentas.