Characterization of Trophoblast-Reactive Monoclonal Antibodies by Flow Cytometry and Their Application for Fetal Cell Isolation

Fetal cells derived from various tissues are often seen within the intervillous space of the placenta, and the transfer of embryonic cells to maternal blood has been documented. The presence of trophoblasts (TBs) in the peripheral circulation has been demonstrated by numerous groups using monoclonal antibodies (mAbs) with flow or magnetic cell sorting, followed by detection of Y-chromosome-derived sequences within the isolates by polymerase chain reaction or fluorescence in situ hybridization (FISH). The frequency of circulating TBs obtained in a single case, from a patient carrying a 47,XYY fetus, was approximately one in 10 super(5) nucleated blood cells after preenrichment by gradient fractionation. Circulating TBs are a potential source of fetal cells for noninvasive prenatal diagnosis of genetic disorders. In this paper, we present our strategy for evaluating anti-trophoblast ( alpha TB) mAbs for the isolation of fetal cells from maternal peripheral blood (MPB), and show that TBs circulate during the gestation of normal fetuses. (DBO)