Detection of receptors for immunoglobulin on human placenta by EA rosette formation.

Direct evidence for the existence of Fc receptors on the surface of first trimester and term human placental cells has been obtained by the use of an antibody-coated red cell (EA) rosette assay. The modification of a Ficoll density gradient separation procedure for placental cell population in conjunction with dye uptake experiments, cytocentrifuge preparations and cytological analysis has enabled an identification of the rosette-forming cells in the mature placenta as predominantly, if not entirely, syncytiotrophoblastic. The significance of these findings, together with those demonstrating the presence of cell-surface Fc receptors on the chorionic membrane, are considered in relation to the transmission of immunoglobulin from mother to foetus and to the protection of the foetus as an intra-uterine allograft.