title: CD99 and CD99L2 act at the same site as, but independently of, PECAM-1 during leukocyte diapedesis.
abstract: Leukocyte extravasation depends on various adhesion receptors at endothelial cell contacts. Here we have analyzed how mouse CD99 and CD99L2 cooperate with PECAM-1. We found that antibodies against mouse CD99 and PECAM-1 trap neutrophils between endothelial cells in in vitro transmigration assays. A sequential function, as has been suggested for human PECAM-1 and CD99, could not be demonstrated. In contrast to these in vitro results, blocking CD99 or CD99L2 or gene disruption of PECAM-1 trapped neutrophils in vivo between endothelial cells and the underlying basement membrane as revealed by electron microscopy and by 3-dimensional confocal fluorescence microscopy in the inflamed cremaster tissue. Leukocyte extravasation was inhibited in interleukin-1beta-inflamed peritoneum and in the cremaster by PECAM-1 gene disruption and was further attenuated by blocking antibodies against CD99 and CD99L2. In addition, CD99 and CD99L2 were required for leukocyte extravasation in the cremaster after stimulation with tumor necrosis factor-alpha, where the need for PECAM-1 is known to be bypassed. We conclude that CD99 and CD99L2 act independently of PECAM-1 in leukocyte extravasation and cooperate in an independent way to help neutrophils overcome the endothelial basement membrane.
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Roentgenstrasse 20, Münster, Germany.
authors.forename: M Gabriele
authors.initials: MG
authors.lastname: Bixel
authors.forename: Hang
authors.initials: H
authors.lastname: Li
authors.forename: Bjoern
authors.initials: B
authors.lastname: Petri
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Khandoga
authors.forename: Andrej
authors.initials: A
authors.lastname: Khandoga
authors.forename: Alexander
authors.initials: A
authors.lastname: Zarbock
authors.forename: Karen
authors.initials: K
authors.lastname: Wolburg-Buchholz
authors.forename: Hartwig
authors.initials: H
authors.lastname: Wolburg
authors.forename: Lydia
authors.initials: L
authors.lastname: Sorokin
authors.forename: Dagmar
authors.initials: D
authors.lastname: Zeuschner
authors.forename: Sigrid
authors.initials: S
authors.lastname: Maerz
authors.forename: Stefan
authors.initials: S
authors.lastname: Butz
authors.forename: Fritz
authors.initials: F
authors.lastname: Krombach
authors.forename: Dietmar
authors.initials: D
authors.lastname: Vestweber
mesh_terms: D000071443:12E7 Antigen; D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D001485:Basement Membrane / Q000276:immunology / Q000378:metabolism; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007249:Inflammation; D007962:Leukocytes / Q000166:cytology / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009504:Neutrophils / Q000276:immunology / Q000378:metabolism; D010537:Peritoneum / Q000276:immunology; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000502:physiology*
chemical_list: D000071443:12E7 Antigen; D015703:Antigens, CD; C522605:Cd99 protein, mouse; D019408:Platelet Endothelial Cell Adhesion Molecule-1