METHODS TO PRODUCE STAGE-SPECIFIC MONOCLONAL-ANTIBODIES AGAINST MOUSETROPHOBLAST CELLS BY INTRASPLENIC AND INVITRO IMMUNIZATIONS

Monoclonal antibodies recognizing epitopes expressed by invasive mouse trophoblast cells were obtained by immunizing male mice of the NMRI s train with mouse egg-cylinders obtained by culturing blastocysts on ag arose for 4 days. Immunization was achieved by intrasplenic and in vit ro methods. The procedures described outline a rational way of produci ng and selecting antibodies which are stage-specific for the mouse tro phoblast at implantation and early placentation.Preimplantation stage- specificity was tested and adhesive blastocysts only were detected by 4 antibodies. Thus, these antibodies become markers for that developme ntal stage which characterizes an adhesive blastocyst ready to implant . Postimplantation stage-specificity was demonstrated by 6 antibodies, which labelled trophoblast cells of day 7 implantations only. Thus, t here is a specific expression of some epitopes by the invasive trophob last. Cell surface epitopes were detected on adhesive blastocysts by 4 antibodies and on the invasive trophoblast of the egg-cylinder by 7 a ntibodies. Shedded antigens from egg-cylinders in vitro were detected by 5 antibodies. Four of these antibodies detected substances released only from early implantation stages. A functional effect was demonstr ated for an IgM antibody which impaired hatching and outgrowth of blas tocysts in vitro.