[Expression of histocompatibility antigens in human pre-implantation embryos]

The expression of HLA antigens on polyploid human preimplantation embryos, obtained in an in vitro fertilization program, was investigated by indirect immunofluorescence test using a panel of well-defined monoclonal antibodies. Neither HLA class I antigens and beta 2-microglobulin, nor HLA class II molecules could be detected on blastomeres and the zona pellucida. It is supposed that the absence of HLA antigens on human preimplantation embryos may be one of the mechanisms important for the acceptance of the embryo by the immunocompetent mother.