title: Selective expression of sialyl-Lewis x and Lewis a epitopes, putative ligands for L-selectin, on peripheral lymph-node high endothelial venules.
abstract: High endothelial venules (HEV) lined by the high endothelium are the sites where leukocytes enter into the lymph nodes from the blood. Lymphocyte homing into lymph nodes is organ-selective, i.e., different molecules are involved in the lymphocyte homing to peripheral nodes compared with mucosa associated lymphoid tissue. The traffic into peripheral nodes is regulated by the expression of L-selectin on leukocytes and its ligand on HEVs. The ligand for L-selectin is suggested to be a 50, 90, or 105 kd glycoprotein, which is sulfated, fucosylated, and sialylated. The two other members of the selectin family (E- and P-selectin) recognize sialyl-Lewis x and -Lewis a (sLex and sLea, respectively) carbohydrate motifs, and there is preliminary data suggesting that this would also be the case for L-selectin. We have initiated a study to identify the expression of these sialylated structures on endothelial surfaces. We present data that show that HEVs in peripheral nodes, but not in the mucosa-associated lymphoid tissue, express large quantities of sLex and sLea identified by MAbs in immunohistology. Endothelium in capillaries or larger vessels in non-lymphoid tissues do not react with anti-sLex or -Lea mAbs. Only 1-2% of the lymphocytes in the peripheral blood express sLex and so far only the skin-homing lymphocytes are known to be sLex positive in larger quantities. We show that in many occasions the B cells in the peripheral lymph-node germinal centers are also sLex-, but not sLea-positive, and provide evidence of the restricted pattern of sLex and sLea expression on peripheral lymph-node HEVs. We propose that they are at least parts of the ligand for L-selectin.
mesh_terms: D000911:Antibodies, Monoclonal; D002241:Carbohydrates / Q000032:analysis / Q000737:chemistry; D015815:Cell Adhesion Molecules / Q000032:analysis* / Q000737:chemistry; D004730:Endothelium, Vascular / Q000737:chemistry* / Q000166:cytology; D000939:Epitopes / Q000032:analysis* / Q000737:chemistry; D006801:Humans; D007150:Immunohistochemistry; D019041:L-Selectin; D007983:Lewis Blood Group Antigens / Q000276:immunology*; D016256:Lewis X Antigen / Q000276:immunology*; D008024:Ligands; D008198:Lymph Nodes / Q000098:blood supply*; D014699:Venules / Q000737:chemistry* / Q000166:cytology
chemical_list: D000911:Antibodies, Monoclonal; D002241:Carbohydrates; D015815:Cell Adhesion Molecules; D000939:Epitopes; D007983:Lewis Blood Group Antigens; D016256:Lewis X Antigen; D008024:Ligands; D019041:L-Selectin