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

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