The Expression of Epithelial Antigens by Trophoblasts and Tumor Cells Using Monoclonal Antibodies to Human Amnion (GB3 and GB5)

The differentiation processes of the amnion and the chorion take place simultaneously with the development of the human embryo (Boyd and Hamilton, 1970). The amnion has been considered to be derived from the trophoblasts which adjoin to the embryonic ectoderm (Bourne, 1962). At term, the amniotic epithelium of reflected and placental amnion lines the amniotic cavity, wraps around the umbilical cord and continues with the fetal skin. By using polyclonal antibodies to human amnion, three groups of antigens in common with some ectodermal tissues were identified (Hsi et al., 1984a). Recently, eight monoclonal antibodies in human amnion have been reported (Hsi and Yeh, 1986). Among them, GB3 reacted with epithelial basement membranes, but the antigen was not among the known ubiquitous components of basement membranes and GB5 recognized the junctional substances of epithelial cells. These antigens are likely to contribute to the cohesion with the subjacent tissues and to the intercellular binding of the epithelium. We report here the expression of these epithelial antigens by trophoblasts in chorion laeve and basal plate, as well as that of breast tumor cells.