title: The autoantibodies to alpha 6 beta 4 integrin of patients affected by ocular cicatricial pemphigoid recognize predominantly epitopes within the large cytoplasmic domain of human beta 4.
abstract: This study was undertaken to characterize the antigenic determinants recognized by the autoantibodies of patients with ocular cicatricial pemphigoid (OCP). OCP is a subepithelial, blistering, autoimmune disease that mainly affects the conjunctiva and other mucous membranes. We previously demonstrated that a cDNA clone, isolated from a keratinocyte expression library by using immunoaffinity-purified OCP autoantibody, encoded the cytoplasmic domain of beta 4 integrin subunit. Our subsequent studies showed that sera from all the OCP patients that were tested recognize the human beta 4 integrin subunit. To identify the prevalent epitopes of the anti-beta 4 autoantibodies of OCP, we have used cell lines transfected with vectors encoding a wild-type beta 4 subunit, a tailless beta 4 subunit, or a beta 4 subunit lacking the extracellular domain. Nontransfected cell lines were used as controls. Lysates from these cell lines were analyzed with OCP sera, IgG fractions from OCP sera, and immunoaffinity-purified OCP autoantibodies. Abs to extracellular and cytoplasmic domains of human beta 4 integrin were used as positive controls, whereas normal human sera and normal human IgG fractions were used as negative controls. The reactivity of OCP Abs was determined by using immunoblotting, immunoprecipitation, and FACS analysis. The results of this study indicate that OCP sera, OCP IgG fractions, and immunoaffinity-purified OCP autoantibodies react with the intracellular and not the extracellular domain of human beta 4 integrin subunit. In vitro cell culture experiments demonstrated that OCP autoantibody binds to the cytoplasm of the cells. The relevance of these findings to the pathogenesis of OCP is discussed.
authors.affiliation: Department of Oral Medicine and Diagnostic Sciences, Harvard School of Dental Medicine, Boston, MA 02115, USA.
authors.forename: K C
authors.initials: KC
authors.lastname: Bhol
authors.forename: M J
authors.initials: MJ
authors.lastname: Dans
authors.forename: R K
authors.initials: RK
authors.lastname: Simmons
authors.forename: C S
authors.initials: CS
authors.lastname: Foster
authors.forename: F G
authors.initials: FG
authors.lastname: Giancotti
authors.forename: A R
authors.initials: AR
authors.lastname: Ahmed
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions / Q000235:genetics; D015703:Antigens, CD / Q000235:genetics / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology*; D001323:Autoantibodies / Q000378:metabolism*; D001327:Autoimmune Diseases / Q000276:immunology*; D002460:Cell Line; D003231:Conjunctivitis / Q000276:immunology*; D003593:Cytoplasm / Q000276:immunology* / Q000378:metabolism; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism*; D005434:Flow Cytometry; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D015151:Immunoblotting; D039161:Integrin alpha6beta4; D039663:Integrin beta4; D016023:Integrins / Q000276:immunology*; D010390:Pemphigoid, Benign Mucous Membrane / Q000276:immunology*; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D051381:Rats; D017384:Sequence Deletion; D014162:Transfection; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics / Q000276:immunology
chemical_list: D015703:Antigens, CD; D000954:Antigens, Surface; D001323:Autoantibodies; D000939:Epitopes; D039161:Integrin alpha6beta4; D039663:Integrin beta4; D016023:Integrins