title: Ultrastructural localization of platelet endothelial cell adhesion molecule (PECAM-1, CD31) in vascular endothelium.
abstract: The distribution of platelet endothelial cell adhesion molecule (PECAM-1, CD31) in vascular endothelium has been disputed. Originally reported to be highly concentrated at interendothelial cell contacts, recent studies have claimed that CD31 is distributed evenly over the entire endothelial cell surface. We re-investigated this question with two different murine anti-CD31 antibodies (MEC 13.3 and M-20), using a pre-embedding immunonanogold electron microscopic procedure that allowed precise label quantitation. MEC 13.3 reacted strongly with the luminal and abluminal plasma membranes of the endothelial cells lining microvessels in normal tissues and in angiogenic vessels induced by a tumor and vascular endothelial growth factor (VEGF-A164). Lateral plasma membranes were significantly less labeled. Conversely, M-20 strongly labeled the cytoplasmic face of the lateral plasma membranes of endothelial cells, although sparing specialized junctions, and only weakly labeled the luminal and abluminal plasma membranes. Both antibodies stained a significant minority of vesicles and vacuoles comprising the vesiculovacuolar organelle (VVO). Neither antibody was reactive in CD31-null mice. We conclude that CD31 is distributed over the entire endothelial cell surface, exclusive of specialized junctions, and in VVOs, but is not equally accessible to different antibodies in all locations.
authors.affiliation: Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
authors.forename: Dian
authors.initials: D
authors.lastname: Feng
authors.forename: Janice A
authors.initials: JA
authors.lastname: Nagy
authors.forename: Kathryn
authors.initials: K
authors.lastname: Pyne
authors.forename: Harold F
authors.initials: HF
authors.lastname: Dvorak
authors.forename: Ann M
authors.initials: AM
authors.lastname: Dvorak
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000918:Antibody Specificity; D015703:Antigens, CD; D015820:Cadherins / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism* / Q000648:ultrastructure*; D005260:Female; D005822:Genetic Vectors; D007150:Immunohistochemistry; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply; D051379:Mice; D008819:Mice, Nude; D008833:Microcirculation; D008854:Microscopy, Electron; D009368:Neoplasm Transplantation; D018919:Neovascularization, Physiologic; D009928:Organ Specificity; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism*; D012867:Skin / Q000098:blood supply; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics; D000099152:Cadherin 5
chemical_list: D015703:Antigens, CD; D015820:Cadherins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D000099152:Cadherin 5