A monoclonal antibody to an antigen present on the microvillous membrane of the trophectoderm of the preimplantation blastocyst of the pig.

Immunization of BALB/c mice with 14-day pig preimplantation blastocyst material followed by fusion of spleen cells with NS-0 myeloma cells resulted in a clone, SN 1/38, which secreted IgG1 which reacted specifically with the microvillous border of the pig trophectoderm and trophoblast as assessed by immunohistology. SN 1/38 did not react with other fetal tissues, or with blastocysts from other animal species. It was shown by absorption studies and by enzyme-linked immunoabsorbent assay that SN 1/38 was not directed against the placental form of pig alkaline phosphatase. The location of this antigen and its apparent presence throughout gestation indicate a functional role in the materno-fetal interaction.