Molecular identification of a novel fibrinogen binding site on the first domain of ICAM-1 regulating leukocyte-endothelium bridging.
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.
Duperray
A
A
Commissariat l'Energie Atomique, Laboratoire d'Hématologie, Département de Biologie Moléculaire et Structurale, INSERM U-217, Grenoble, France.
Languino
L R
LR
Plescia
J
J
McDowall
A
A
Hogg
N
N
Craig
A G
AG
Berendt
A R
AR
Altieri
D C
DC
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
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D008024:Ligands; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1; D005340:Fibrinogen