Identification of extra-villous trophoblast cells in human decidua using an apparently unique murine monoclonal antibody to trophoblast.

Murine monoclonal antibodies were raised to human first trimester trophoblast cells. Eleven antibodies reacted with first trimester trophoblast, tested by immunoperoxidase staining on frozen sections, but only one had apparent specificity for trophoblast after examining reactivities with a panel of other cells and tissues. This antibody, designated FD0161G, bound selectively to syncytiotrophoblast and non-villous trophoblast in first trimester and term placentae. Villous cytotrophoblast was negative. This was clearly demonstrated on freeze-dried, paraffin embedded tissue sections which have superior architecture to frozen sections. FD0161G reacted with extra-villous trophoblast cells in human decidua which are also delineated by a monoclonal anti-cytokeratin antibody. Unlike the latter, however, FD0161G did not react with decidual glands. Thus FD0161G could be used as a specific probe for extra-villous trophoblast in decidual tissue.