Functional distribution and further characterization of human endothelial ligand for cellular L-selectin

In the present study we examine the functional distribution of the human en dothelial L-selectin ligand, which determines the sites of extravasation of L-selectin-positive cells, A murine cell line transfected with human L-sel ectin adhered preferentially to the high endothelial venules (HEV) of human peripheral lymph nodes compared to the HEV of mucosal lymphoid tissues (me an of 0.83 compared to a mean of 0.07 cells per HEV respectively). In addit ion, an antibody against L-selectin differentially inhibited the adhesion o f human lymphocytes to peripheral lymphoid tissue versus mucosal lymphoid t issue HEV (mean 41 and 5% inhibition respectively). Although both sulfogluc uronyl-containing glycolipids and sialyl-Lewis X have been proposed as endo thelial ligands for L-selectin, an antibody against the former did not bind to peripheral lymph node endothelium, and an antibody against the latter d id not block adhesion of L-selectin-expressing cells. The enzyme O-sialogly coprotein endopeptidase caused up to an 84% reduction in L-selectin-depende nt binding, indicating that sialylated glycoproteins containing O-linked gl ycans are essential for a large majority of adhesion via L-selectin.