APOL1 and preeclampsia: The role of maternal monocytes and macrophages in preeclampsia has been investigated in human placenta tissue and in rat models.38,39 Maternal monocytes become activated during their passage through the placenta.40 APOL1 was detected in plasma of dams with both BAC/APOL1 and Alb/APOL1 fetuses, although at a low level.