Isolation and characterisation of a subpopulation of human chorionic cytotrophoblast using a monoclonal anti-trophoblast antibody (NDOG2) in flow cytometry

Human cytotrophoblast cells, isolated from term amniochorion by enzymic digestion and Percoll gradient centrifugation, were characterised by flow cytometry. A panel of 12 anti-trophoblast monoclonal antibodies was screened for labelling of these cells in flow cytometry and the results compared with immunoperoxidase labelling of cytospin preparations and tissue sections. All 12 antibodies were positive for trophoblast on tissue sections, 11 12 were positive on cytospins but only two (NDOG2 and GB25) gave consistent results in flow cytometry. Two-colour labelling with NDOG2 and W6/32, an antibody to HLA-A, -B, -C, demonstrated that 88% of the NDOG2-positive cells also express Class I major histocompatibility complex (MHC) antigens. The NDOG2-positive cytotrophoblast subpopulation was isolated by flow cytometry in sufficient purity (>95%) and yield (3.1 × 10 6) for use in functional studies in vitro.