Disappearance of paternal histocompatibility antigens from hybrid mouse blastocyst at the time of implantation

Abstract
Products of the major histocompatibility complex (H-2) are important in allograph rejection. In view of the close relationship between mother and foetus, we can consider the latter as an allograph which is however not rejected by an immunological reaction. We studied the presence of H-2 antigens on embryo membranes at the time of implantation, by immunochemical labeling using gold particles coupled with protein A. Results showed that the expression of H-2 antigens is different before and after implantation. It seems that after implantation, H-2 antigens disappear from trophoblastic membranes. This could explain the absence of immunological reaction of the mother against the foetus.