Cell surface carbohydrate in cell adhesion. Sperm cells and leukocytes bind to their target cells through specific oligosaccharide ligands.

During the past few years it has become increasingly evident that specific oligosaccharides in glycoproteins/glycolipids may play a central role in mammalian cell adhesion. This review deals with two of the best studied systems, the interaction of sperm cells with the Zona pellucida layer surrounding mammalian eggs, and the binding of leukocytes to endothelial cells. In the sperm cell-Zona pellucida system, it is known that a specific oligosaccharide(s) in the Zona pellucida glycoprotein 3 is responsible for binding. In the leukocyte-endothelial cell interaction, sialyl Le(x), sialyl Le(a), sulfatides, and other less well-defined sugar structures are involved in cellular binding. Oligosaccharides involved in these adhesion events may turn out to have clinically important applications.