Interactions between lymphocyte surface receptors and their ligands on vascular endothelial cells regulate the exit of lymphocytes from the circulation. Distinct subsets of mononuclear cells bind to high endothelial venules (HEVs) in different lymphoid organs to a different extent, but the molecular mechanisms behind this selectivity have remained poorly characterized. Here we show that vascular adhesion protein-1 (VAP-1) mediates subtype-specific binding of CD8-positive T cells and natural killer cells to human endothelium. VAP-1–dependent, oligosaccharide-dependent peripheral lymph node (PLN) HEV adhesion under shear was independent of L-selectin, P-selectin glycoprotein ligand 1, and α4 integrins, the known lymphocyte receptors involved in the initial recognition of endothelial cells. PLN HEV adhesion was also critically dependent on peripheral lymph node vascular addressins (PNAds), but lymphocyte L-selectin was absolutely required for PNAd binding. Most lymphocytes relied on both PNAd and VAP-1 in HEV binding. The overlapping function of L-selectin ligands and VAP-1 in PLN introduces a new control point into the lymphocyte extravasation process. Finally, intravital microscopy revealed that VAP-1 is involved in initial interactions between human lymphocytes and endothelial cells in inflamed rabbit mesenterial venules in vivo. In conclusion, VAP-1 is a novel contact-initiating ligand that discriminates between different subpopulations of mononuclear cells and is an appealing target for selective modulation of adhesion of CD8- and CD16-positive effector cells.
Vascular Adhesion Protein 1 (VAP-1) Mediates Lymphocyte Subtype-specific, Selectin-independent Recognition of Vascular Endothelium in Human Lymph Nodes
Address correspondence to Marko Salmi, MediCity Research Laboratory, Rm 4021, Tykistökatu 6A, 20520 Turku, Finland. Phone: 368-2-3337007; FAX: 358-2-3337000; E-mail: marko.salmi @utu.fi
Abbreviations used in this paper: HEV, high endothelial venule; MACS, magnetic-activated cell sorting; PLN, peripheral lymph node; PNAd, peripheral lymph node vascular addressin; PSGL-1, P-selectin glycoprotein ligand 1; VAP, vascular adhesion protein.
Marko Salmi, Sami Tohka, Ellen L. Berg, Eugene C. Butcher, Sirpa Jalkanen; Vascular Adhesion Protein 1 (VAP-1) Mediates Lymphocyte Subtype-specific, Selectin-independent Recognition of Vascular Endothelium in Human Lymph Nodes . J Exp Med 18 August 1997; 186 (4): 589–600. doi: https://doi.org/10.1084/jem.186.4.589
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