Studies of human pregnancy. I. Immunoglobulins attached to the trophoblast.

The human placenta was studied for the binding of immunoglobulins IgG, IgM, IgE, and C3 complement to the cell membrane of the trophoblast by use of fluorescein-conjugated and unlabelled antihuman immunoglobulins. Gestations of 8 to 40 weeks were evaluated for placental tissues taken from women undergoing therapeutic abortion, elective induction of labor, cesarean section, spontaneous labor, and toxemia of pregnancy. IgA was increased on the syncytial cytotrophoblast membranes at 8 to 10 weeks' gestation; IgE was present on the surface of the trophoblast only during spontaneous labor; and IgG was observed on the syncytial cytotrophoblastic cell membrane and basement membrane, and in the cytoplasm and the nucleus in all stages of gestation.