Cytoadherence of Plasmodium falciparum-infected erythrocytes in the human placenta

In Plasmodium falciparum-parasitized pregnant women, erythrocytes infected by mature stages of the parasite sequester into placental intervillous spac es. The presence of parasites in the placenta causes maternal anaemia and l ow birth weight of the infant. In-vitro studies suggest placental sequestra tion may involve the cytoadherence of infected erythrocytes to chondroitin sulphate A (CSA) and/or intercellular adhesion molecule 1 (ICAM-1) expresse d by human placental syncytiotrophoblast. We identified P. falciparum recep tors expressed on the surface of human syncytiotrophoblast using immunofluo rescence of placental biopsies from Cameroon, a malaria-endemic area. In al l placentas, a strongly positive staining was observed on the syncytiotroph oblast for CSA, but not for ICAM-1, vascular endothelium cell adhesion mole cule-1, E-selectin, nor CD36. The cytoadherence ability of parasites from p regnant women and nonpregnant subjects was assessed on in-vitro cultured sy ncytiotrophoblast. Parasites from pregnant women bound to the trophoblast v ia CSA but not ICAM-1. Parasites from nonpregnant hosts either did not bind to the trophoblast culture or bound using ICAM-1. Our data support the ide a that placental sequestration may result from cytoadherence to placental t rophoblast and that pregnant women are parasitized by parasites that differ from parasites derived from nonpregnant host by their cytoadherence abilit y.