title: ICAM-3 interacts with LFA-1 and regulates the LFA-1/ICAM-1 cell adhesion pathway.
abstract: The interaction of lymphocyte function-associated antigen-1 (LFA-1) with its ligands mediates multiple cell adhesion processes of capital importance during immune responses. We have obtained three anti-ICAM-3 mAbs which recognize two different epitopes (A and B) on the intercellular adhesion molecule-3 (ICAM-3) as demonstrated by sequential immunoprecipitation and cross-competitive mAb-binding experiments. Immunoaffinity purified ICAM-3-coated surfaces were able to support T lymphoblast attachment upon cell stimulation with both phorbol esters and cross-linked CD3, as well as by mAb engagement of the LFA-1 molecule with the activating anti-LFA-1 NKI-L16 mAb. T cell adhesion to purified ICAM-3 was completely inhibited by cell pretreatment with mAbs to the LFA-1 alpha (CD11a) or the LFA-beta (CD18) integrin chains. Anti-ICAM-3 mAbs specific for epitope A, but not those specific for epitope B, were able to trigger T lymphoblast homotypic aggregation. ICAM-3-mediated cell aggregation was dependent on the LFA-1/ICAM-1 pathway as demonstrated by blocking experiments with mAbs specific for the LFA-1 and ICAM-1 molecules. Furthermore, immunofluorescence studies on ICAM-3-induced cell aggregates revealed that both LFA-1 and ICAM-1 were mainly located at intercellular boundaries. ICAM-3 was located at cellular uropods, which in small aggregates appeared to be implicated in cell-cell contacts, whereas in large aggregates it appeared to be excluded from cell-cell contact areas. Experiments of T cell adhesion to a chimeric ICAM-1-Fc molecule revealed that the proaggregatory anti-ICAM-3 HP2/19 mAb was able to increase T lymphoblast attachment to ICAM-1, suggesting that T cell aggregation induced by this mAb could be mediated by increasing the avidity of LFA-1 for ICAM-1. Moreover, the HP2/19 mAb was costimulatory with anti-CD3 mAb for T lymphocyte proliferation, indicating that enhancement of T cell activation could be involved in ICAM-3-mediated adhesive phenomena. Altogether, our results indicate that ICAM-3 has a regulatory role on the LFA-1/ICAM-1 pathway of intercellular adhesion.
authors.affiliation: Servicio de Inmunologìa, Hospital de la Princesa, Madrid, Spain.
authors.forename: M R
authors.initials: MR
authors.lastname: Campanero
authors.forename: M A
authors.initials: MA
authors.lastname: del Pozo
authors.forename: A G
authors.initials: AG
authors.lastname: Arroyo
authors.forename: P
authors.initials: P
authors.lastname: Sánchez-Mateos
authors.forename: T
authors.initials: T
authors.lastname: Hernández-Caselles
authors.forename: A
authors.initials: A
authors.lastname: Craig
authors.forename: R
authors.initials: R
authors.lastname: Pulido
authors.forename: F
authors.initials: F
authors.lastname: Sánchez-Madrid
mesh_terms: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D007700:Kinetics; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism*; D011233:Precipitin Tests; D013601:T-Lymphocytes / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000943:Antigens, Differentiation; D015815:Cell Adhesion Molecules; C483616:ICAM3 protein, human; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1