Frozen sections of human placentae taken at selected stages throughout gestation were
stained with monoclonal antibodies to HLA-A, B, C and DR antigens, using an indirect
immunoperoxidase technique. No staining of villous trophoblastic tissue was detected.
Antibody to HLA-A, B, and C antigens clearly stained membranous elements of the villous
stroma. Antibody to HLA-DR antigens stained rare, elongated cells of the villous stroma in
the term placenta. Monoclonal antibodies to syncytiotrophoblast membrane were used as a …