title: Endothelial CD99 supports arrest of mouse neutrophils in venules and binds to neutrophil PILRs.
abstract: CD99 is a crucial regulator of the transmigration (diapedesis) of leukocytes through the blood vessel wall. Here, we report that CD99 acts at 2 different steps in the extravasation process. In agreement with previous antibody-blocking experiments, we found that CD99 gene inactivation caused neutrophil accumulation between venular endothelial cells and the basement membrane in the inflamed cremaster. Unexpectedly, we additionally found that leukocyte attachment to the luminal surface of the venular endothelium was impaired in the absence of CD99. Intravital video microscopy revealed that CD99 supported rapid chemokine-induced leukocyte arrest. Inhibition of leukocyte attachment and extravasation were both solely due to the absence of CD99 on endothelial cells, whereas CD99 on leukocytes was irrelevant. Therefore, we searched for heterophilic ligands of endothelial CD99 on neutrophils. We found that endothelial cells bind to the paired immunoglobulinlike receptors (PILRs) in a strictly CD99-dependent way. In addition, endothelial CD99 was coprecipitated with PILRs from neutrophils that adhered to endothelial cells. Furthermore, soluble CD99 carrying a transferable biotin tag could transfer this tag covalently to PILR when incubated with intact neutrophils. Binding of neutrophils under flow to a surface coated with P-selectin fragment crystallizable (Fc) and intercellular adhesion molecule 1 (ICAM-1) Fc became more shear resistant if CD99 Fc was coimmobilized. This increased shear resistance was lost if neutrophils were preincubated with anti-PILR antibodies. We concluded that endothelial CD99 promotes leukocyte attachment to endothelium in inflamed vessels by a heterophilic ligand. In addition, CD99 binds to PILRs on neutrophils, an interaction that leads to increased shear resistance of the neutrophil attachment to ICAM-1.
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Debashree
authors.identifier: 0000-0001-5878-0482
authors.initials: D
authors.lastname: Goswami
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Sigrid
authors.initials: S
authors.lastname: März
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Yu-Tung
authors.initials: YT
authors.lastname: Li
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Annette
authors.initials: A
authors.lastname: Artz
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Schäfer
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Ruth
authors.initials: R
authors.lastname: Seelige
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Mariana
authors.initials: M
authors.lastname: Pacheco-Blanco
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Ding
authors.initials: D
authors.lastname: Jing
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Maria Gabriele
authors.initials: MG
authors.lastname: Bixel
authors.affiliation: Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan.
authors.forename: Masatake
authors.initials: M
authors.lastname: Araki
authors.affiliation: Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan.
authors.forename: Kimi
authors.initials: K
authors.lastname: Araki
authors.affiliation: Institute of Resource Development and Analysis, Kumamoto University, Kumamoto, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Yamamura
authors.affiliation: Max Planck Institute of Molecular Biomedicine, Münster, Germany; and.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Vestweber
mesh_terms: D000071443:12E7 Antigen / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion; D002465:Cell Movement; D004730:Endothelium, Vascular; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007962:Leukocytes / Q000166:cytology; D051379:Mice; D009504:Neutrophils / Q000378:metabolism; D011485:Protein Binding; D011971:Receptors, Immunologic / Q000378:metabolism*
chemical_list: D000071443:12E7 Antigen; C522605:Cd99 protein, mouse; C548037:PILRalpha protein, mouse; C548038:PILRbeta protein, mouse; D011971:Receptors, Immunologic; D018799:Intercellular Adhesion Molecule-1