title: Molecular identification of a novel fibrinogen binding site on the first domain of ICAM-1 regulating leukocyte-endothelium bridging.
abstract: Binding of fibrinogen to intercellular adhesion molecule 1 (ICAM-1) enhances leukocyte adhesion to endothelium by acting as a bridging molecule between the two cell types. Here, a panel of four monoclonal antibodies (mAbs) to ICAM-1 was used to dissect the structure-function requirements of this recognition. All four mAbs bound to ICAM-1 transfectants and immunoprecipitated and immunoblotted ICAM-1 from detergent-solubilized JY lymphocyte extracts. Functionally, mAbs 1G12 and 2D5 inhibited binding of 125I-fibrinogen to ICAM-1-transfectants and abrogated the enhancing effect of fibrinogen on mononuclear cell adhesion to endothelium and transendothelial migration. In contrast, mAbs 3D6 and 6E6 did not affect ICAM-1 recognition of fibrinogen. With respect to other ligands, mAbs 1G12 and 2D5 completely inhibited attachment of Plasmodium falciparum-infected erythrocytes to immobilized recombinant ICAM-1-Fc, whereas they had no effect on LFA-1-dependent T cell binding to ICAM-1-Fc. Conversely, mAbs 3D6 and 6E6 completely abolished LFA-1 binding to ICAM-1-Fc. Epitope assignment using ICAM-1 chimeras and receptor mutants revealed that the fibrinogen-blocking mAbs 1G12 and 2D5 reacted with domain 1 of ICAM-1, and their binding was disrupted by 97 and 70% by mutations of D26 and P70, respectively, whereas mAbs 3D6 and 6E6 bound to domain 2 of ICAM-1. By recognizing a site distinct from that of beta2 integrins Mac-1 or LFA-1, fibrinogen binding to ICAM-1 may provide an alternative pathway of intercellular adhesion and/or modulate integrin-dependent adherence during inflammation and vascular injury.
authors.affiliation: Commissariat l'Energie Atomique, Laboratoire d'Hématologie, Département de Biologie Moléculaire et Structurale, INSERM U-217, Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Duperray
authors.forename: L R
authors.initials: LR
authors.lastname: Languino
authors.forename: J
authors.initials: J
authors.lastname: Plescia
authors.forename: A
authors.initials: A
authors.lastname: McDowall
authors.forename: N
authors.initials: N
authors.lastname: Hogg
authors.forename: A G
authors.initials: AG
authors.lastname: Craig
authors.forename: A R
authors.initials: AR
authors.lastname: Berendt
authors.forename: D C
authors.initials: DC
authors.lastname: Altieri
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D018604:Epitope Mapping; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D007962:Leukocytes / Q000166:cytology*; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D011485:Protein Binding
chemical_list: D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1; D005340:Fibrinogen