Novel chondroitin sulfate-modified ligands for L-selectin on lymph node high endothelial venules

The migration of lymphocytes into lymph nodes via high endothelial venules (HEV) is dependent on the expression of L-selectin on the lymphocyte cell s urface. HEV express several L-selectin ligands including CD34, GlyCAM-1, MA dCAM-1 and two sulfated glycoproteins (Sgp) of 200 kDa and 170 kDa which re main to be identified. In this investigation, labeling with sodium [S-35]su lfate, which is incorporated into and forms part of the functional carbohyd rate ligand, has been used to isolate and characterize macromolecular L-sel ectin ligands. High endothelia[ cells (HEC) cultured from rat lymph node HE V were shown to express ligands for L-selectin. HEC synthesized two groups of sulfated glycoproteins of 150 kDa and > 200 kDa, which were present in c onditioned medium. These coeluted on anion exchange chromatography at 1.0-1 .2 M NaCl and supported calcium-dependent L-selectin-mediated cell adhesion . In common with known L-selectin ligands, Sgp 150/> 200 were shown to be O -sialoglycoproteins; however, in contrast to other ligands, Sgp 150/> 200 c ontained chondroitin sulfate glycosaminoglycan modifications which were req uired for L-selectin recognition. Chondroitin sulfate-modified ligands for L-selectin were expressed at the HEC surface and by HEV in lymph nodes, sug gesting that they may participate in lymphocyte interactions with HEV in vi vo.