6'-sulfo sialyl Le(x) but not 6-sulfo sialyl Le(x) expressed on the cell surface supports L-selectin-mediated adhesion

In order to determine if a sulfated oligosaccharide on the cell surface can function as an L-selectin ligand, a novel approach for in vitro transfer of oligosaccharides was utilized (Srivastava, G., Kaun, K. J., Hindsgaul, O., and Palcic, M. M. (1992) J. Biol. Chem. 267, 22356-22361). CHO cells were incubated with synthetic 6'-sulfo sialyl Le(x), NeuNAcα2→3(sulfate- 6)Galβ1→4(Fucα1→3)GlcNAc or 6-sulfo sialyl Le(x), NeuNAcα2→3Galβ1→4[(Fucα1→3)sulfate→6GlcNAc] oligosaccharide linked to C-6 of a fucose residue in GDP-fucose and a milk fucosyltransferase. The resultant CHO cells expressing 6'-sulfo sialyl Le(x) or 6-sulfo sialyl Le(x) on their cell surface were tested for adhesion to E-selectin and L-selectin chimeric proteins coated on plates. The results indicate that 6'-sulfo sialyl Le(x) supports L-selectin-mediated adhesion much better than sialyl Le(x) similarly tagged on the cell surface. In contrast, 6-sulfo sialyl Le(x) containing a sulfate group on the N-acetylglucosamine residue did not support adhesion with either selectin. These combined results suggest that 6'-sulfo sialyl Le(x) is a much better ligand than sialyl Le(x) oligosaccharide for L- selectin.