A crucial effect of ligand clustering on the inhibition of binding by L-selectin in intercellular adhesion.

Glucan sulfates were found to be potent ligands for L-selectin by a quantitative liquid phase analysis system (Yoshida, T. et al., Eur. J. Biochem., in press). The affinity of glucan sulfates to L-selectin-IgG chimera was dependent on the size of the glucan sulfates as well as on the inter-glucose linkages. In the current report, these glucan sulfates are shown to inhibit the interaction of an endothelial cell line with lymphocytes. The effect of ligand size appears to be more remarkable in the cell-cell binding than in the liquid phase analysis. The affinity of amylose sulfate continues to increase, as their size increases even beyond 12 kDa, at which its affinity reached a plateaux in the liquid phase analysis.