GIyCAM-1 supports leukocyte rolling in flow: Evidence for a greater dynamic stability of L-selectin rolling of lymphocytes than of neutrophils

Abstract

L-selectin plays a major role in leukocyte traffic through lymph node high endothelial venules (HEV). We have investigated the role of GIyCAM-1, a major L-selectin ligand produced by HEV, in mediating leukocyte rolling under in vitro flow conditions. Purified GIyCAM-1 was found to support tethering and rolling in physiological shear flow of both human and murine L-selectin expressing leukocytes at an efficiency comparable to the HEV-derived L-selectin ligands termed peripheral node addressin (PNAd). Major dynamic differences between L-selectin rolling of peripheral blood T lymphocytes and neutrophils expressing similar L-selectin level were observed on GIyCAM-1. Lymphocytes established slower and more shear resistant rolling than neutrophils and could roll on GIyCAM-1 at shear stresses lower than the threshold values required for L-selectinmediated neutrophil rolling. Notably, high stability of L-selectin rolling of lymphocytes requires intact cellular energy, although initial lymphocyte tethering to L-selectin ligands is energy-independent. By contrast, L-selectin mediated rolling of neutrophils is insensitive to energy depletion. The distinct dynamic behavior and energy-dependence of L-selectin rolling in different leukocytes suggest that L-selectin adhesiveness in shear flow is regulated in a cell-type specific manner. The greater stability of L-selectin rolling of lymphocytes on surface-adsorbed GIyCAM-1 may contribute to their selective recruitment at peripheral lymph nodes.

Key Words:

• Selectins
• leukocytes
• rolling
• homing