Binding of antigen-antibody complexes to mononuclear phagocytes in chorionic villi of human placentae.

Both endogenous placental IgG and exogenous antigen-antibody complexes are bound to stromal cells within the chorionic villi of human placentae. Both types of IgG are removed readily from placentae by washing at pH 5.0, while antibodies to placental antigens, when reacted with the villi, are not removed except under very low pH conditions (pH 2.5). Furthermore, when IgG is removed from term placentae and characterized by filtration chromatography, most of the IgG is seen to occur either as IgG fragments or as complexes of greater than 200000 relative molecular mass. This suggests that placental IgG exists as Fc gamma receptor-associated antigen-antibody complexes.