title: Homotypic leukocyte aggregation triggered by a monoclonal antibody specific for a novel epitope expressed by the integrin beta 1 subunit: conversion of nonresponsive cells by transfecting human integrin alpha 4 subunit cDNA.
abstract: The monoclonal antibody 33B6 was found to be specific for the beta 1 integrin subunit. Treatment of leukocytes with this antibody induced a vigorous homotypic aggregation that had similar physiologic conditions as aggregation induced by a monoclonal antibody specific for the alpha 4 subunit. Expression of a beta 1 subunit on the cell surface was not sufficient for mAb 33B6-mediated aggregation to occur, since cells of the K562 erythroleukemia line failed to respond even though they expressed the beta 1 subunit and the 33B6 epitope. However, after transfection with cDNA encoding the alpha 4 subunit, K562 cells acquired the ability to aggregate in response to mAb 33B6 binding. By contrast, mAb 33B6 blocked cell binding to the endothelial surface protein vascular cell adhesion molecule-1 and the extracellular matrix protein fibronectin. These results suggest that the beta 1 epitope defined by mAb 33B6 may play a novel role in regulating leukocyte adhesive interactions.
authors.affiliation: Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
authors.forename: J L
authors.initials: JL
authors.lastname: Bednarczyk
authors.forename: J N
authors.initials: JN
authors.lastname: Wygant
authors.forename: M C
authors.initials: MC
authors.lastname: Szabo
authors.forename: L
authors.initials: L
authors.lastname: Molinari-Storey
authors.forename: M
authors.initials: M
authors.lastname: Renz
authors.forename: S
authors.initials: S
authors.lastname: Fong
authors.forename: B W
authors.initials: BW
authors.lastname: McIntyre
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002449:Cell Aggregation; D002461:Cell Line, Transformed; D004247:DNA / Q000235:genetics; D000939:Epitopes / Q000276:immunology; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007153:Immunologic Deficiency Syndromes / Q000473:pathology; D039041:Integrin alpha4beta1; D016023:Integrins / Q000276:immunology* / Q000378:metabolism; D004915:Leukemia, Erythroblastic, Acute; D007962:Leukocytes / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D014162:Transfection; D014407:Tumor Cells, Cultured; D019010:Vascular Cell Adhesion Molecule-1
chemical_list: D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; D000939:Epitopes; D005353:Fibronectins; D007074:Immunoglobulin G; D039041:Integrin alpha4beta1; D016023:Integrins; D011993:Recombinant Fusion Proteins; D019010:Vascular Cell Adhesion Molecule-1; D004247:DNA