Effects of monoclonal antibody directed to LeY on implantation in the mouse

The role of carbohydrates in embryo implantation in the mouse wasinvestigated using an embryo transfer model and a blastocyst-uterineepithelial cell co-culture system. The monoclonal antibody (mAb) AH6directed to LeY oligosaccharide (Fuc alpha1-2 Gal beta 1-4 [Fuc alpha1- 3]GlcNAc) and other three mAbs directed to carbohydrates whose structures areclosely related to LeY were used to show the effect of carbohydratespecificity on implantation. In the embryo transfer model, donorblastocysts (4 days post-coitus) were pretreated with mAb AH6(experimental) or other mAbs (control) and transferred into one uterinehorn of a recipient. The implantation rate was checked after 5 days.Implantation was significantly inhibited by mAb AH6 pretreatment, andinhibition was not observed in control groups. In the co-culture system,the attachment and outgrowth rate of blastocysts on the surface of uterineepithelial cells was significantly inhibited when monolayer epithelialcells or blastocysts were pretreated with mAb AH6. The most obvious effectof mAb AH6 was obtained during 2-4 h co-incubation. No inhibition wasobserved in the control groups. It was, therefore, concluded thatoligosaccharide LeY recognized by mAb AH6 plays an essential role at theinitial stage of implantation. It may act as a mediator molecule foradhesion between the surface of blastocyst and epithelial cell, and itsfunction is carbohydrate-specific.