The role of antibody to human beta4 integrin in conjunctival basement membrane separation: possible in vitro model for ocular cicatricial pemphigoid.

PURPOSE To demonstrate the specific binding of autoantibodies present in the sera of patients with ocular cicatricial pemphigoid (OCP) to human beta4 integrin present in the normal human conjunctiva (NHC) and to study the role of OCP autoantibodies and antibody to human beta4 integrin in the pathogenesis of subepithelial lesion formation in OCP. METHODS Indirect immunofluorescence assay and in vitro organ culture method using NHC were used. Sera and IgG fractions from 10 patients with OCP; immunoaffinity-purified OCP autoantibody; antibodies to human beta4, beta1, alpha6, and alpha5 integrins; and sera from patients with pemphigus vulgaris, bullous pemphigoid (BP), and chronic atopic and chronic ocular rosacea cicatrizing conjunctivitis; and normal human serum (NHS) were used. RESULTS Nine of 10 OCP sera or IgG fractions, immunoaffinity-purified OCP autoantibody, antibodies to human beta4 and alpha6 integrins, and sera from patients with BP showed homogenous, smooth linear binding along the basement membrane zone (BMZ) of the NHC. NHS, antibodies to other integrins, and sera from patients with chronic cicatrizing conjunctivitis from other causes showed no such binding. When NHC was first absorbed with OCP sera and then reacted with anti-beta4 antibodies or vice versa, the intensity of the BMZ binding was dramatically reduced or completely eliminated, indicating that there were autoantibodies in OCP sera specific for the beta4 integrin. BMZ separation developed 48 to 72 hours after addition of total OCP sera, IgG fractions from OCP sera, immunoaffinity-purified autoantibodies from sera of patients with OCP, or anti-beta4 antibodies to the NHC cultures, but not after addition of normal control sera, sera from patients with chronic cicatrizing conjunctivitis from causes other than OCP, or sera from patients with OCP in clinical remission. CONCLUSION Circulating anti-beta4 integrin antibody may have an important role in the pathogenesis of OCP.