Severely reduced presence of tissue macrophages in the basal plate of pre-eclamptic placentae

Pre-eclampsia is a disorder of unknown aetiology peculiar to human pregnanc y, a well-described pathological feature being shallow trophoblast invasion into the spiral arteries during placenta development. Epidemiological stud ies have revealed an increased risk in pregnancies of primipaternity, and a n association with the maternal-fetal HLA-DR relationship, both suggesting the involvement of an immunological component. We were therefore interest e d in the distribution of HLA-DR expressing myeloid cells in the decidua of healthy and pre-eclamptic placentae. We have studied the monocytes in mater nal and fetal peripheral blood as well as in the placenta and identified th e cluster of differentiation (CD) 14(+) myeloid cells in the basal plate as mannose receptor (ManR) positive tissue macrophages. In a comparison betwe en peripheral blood monocytes from healthy; pregnant and pre-eclamptic wome n we found no significant difference in the subpopulation size of CD14(+)/C D16(+) monocytes. The number and location of macrophages in the placental v illi was similar. However, while the basal plate of the normal decidua cont ained numerous CD14(+), HLB-DRbright, ManR(+) tissue macrophages, this comp artment was virtually void of these phagocytic cells in the pre-eclamptic p lacenta. This novel finding suggests that in pre-eclampsia not only the mig ration of endovascular cytotrophoblasts is disturbed, but that also materna l macrophage migration is affected. (C) 2001 Harcourt Publishers Ltd.