A MONOCLONAL-ANTIBODY TO HUMAN PLACENTAL-LACTOGEN HORMONE FACILITATESISOLATION OF FETAL CELLS FROM MATERNAL BLOOD IN A MODEL SYSTEM

A cocktail of trophoblast-reactive monoclonal antibodies (MAbs) is req uired for efficient isolation of trophoblasts from maternal blood. A m odified antibody screening procedure was used to identify a clone, in a COS cell placental cDNA expression library, that expressed the gene product recognized by MAb FDO202N. The antigen recognised by MAb FDO20 2N was identified as human placental lactogen (hPL) hormone. hPL hormo ne is secreted into the maternal blood by trophoblasts at high levels during pregnancy. Immunohistochemical localization of hPL hormone was consistent with expression in the syncytiotrophoblast and extravillous cytotrophoblast. A model system was used where known numbers of syncy tiotrophoblast sprouts were seeded into saline or maternal blood, boun d by trophoblast-specific MAbs, recovered magnetically, and then count ed. MAb FDO202N was shown to facilitate the efficient recovery of trop hoblast sprouts from saline and maternal blood.