ANALOGS OF CORD RED-BLOOD-CELL MEMBRANE-COMPONENTS DISPLAYED ON PLACENTA, AMNION AND AMNIOTIC CELLS IN CULTURE

Placenta and amnion were analyzed to ascertain the presence of antigen s in common with red blood cells (RBC) from cord or fetuses. The expre ssion of distinct antigens displayed on a subpopulation of cord RBC an d detected by anti-cord RBC membrane antibodies was particularly inves tigated, concomitantly with the presence of transferrin receptors (TR) by employing immunohistochemistry. The placenta showed both cord anti gen and TR; on the contrary, amnion - which was labelled by anti-cord RBC membrane antibodies - was not stained by the anti-TR antibody. The results of inhibition and double labelling assays further excluded TR as the relevant antigen in the labelling of both placenta and amnion. The staining of fetal membranes disappeared after absorption of antib odies with cord RBC membranes. These results suggest that the antigens externally expressed on a subpopulation of cord RBC are shared by amn ion and placenta.