Influence of oligosaccharide presentation on the interactions of carbohydrate sequence-specific antibodies and the selectins - Observations with biotinylated oligosaccharides

This study was aimed at investigating the efficacy of presentation of bioti nylated oligosaccharides on streptavidin-coated microwells for interactions with (a) three monoclonal antibodies directed at sialyl-lewis(a) (Le(a)) o r sulfo-Le(a)-related sequences, and (b) the endothelium-leukocyte adhesion molecules, the E-, L- and P-selectins which recognize both the sulfo- and sialyl-lea series. With the antibodies it was observed that if the biotinyl ated oligosaccharide incorporated the entire antigenic determinant, and add itional saccharide length was not included, the biotinyl tag spacer length was a critical factor in the strength of the binding signal. If oligosaccha ride chain beyond the determinant was included, the biotinyl tag spacer len gth was less important. The E-selectin binding data with the biotinylated s ialyl- and sulfo-oligosaccharides were in overall accord with previous know ledge. With the L- and P-selectins, however, unexpectedly low binding signa ls were elicited by biotinyl sulfo-Le(a) sequences relative to those with t he sialyl-analogs. This suppression was more pronounced with the rodent tha n the human L-selectin, Such differential availabilities of oligosaccharide s displayed on streptavidin may relate to biological situations, such as th e differential reactivities of the three selectins with a given oligosaccha ride ligand presented on different carrier proteins, or on different O-glyc an cores on mucin-type glycoproteins. (C) 1999 Elsevier Science B.V. All ri ghts reserved.