Identification of autoantibody to melanocytes and characterization of vitiligo antigen in vitiligo patients

Patients with vitiligo have circulating antibodies to melanocytes. To identify vitiligo antibodies and characterize the antigens by vitiligo antibodies, sera of Is patients with vitiligo, 18 with Behcet's disease, 22 with syphilis and 14 normal control subjects were analyzed by indirect immunofluorescence, live cell ELISA, and immunoblotting. In indirect immunofluorescent microscopy and live cell ELISA, most vitiligo sera showed positive immunofluorescence and high optical density on the surface of melanocytes cultured from normal and vitiligo patients, indicating that autoantibodies in the vitiligo sera may react with vitiligo antigens on the surface of melanocytes. When the same experiments were performed with malignant melanoma cell lines and fibroblasts, no significant differences in the immunofluorescence and optical density were observed between normal and vitiligo sera. And the sera of patients with Behcet's disease or syphilis showed no significant difference in the reaction of live cell ELISA to fibroblasts, IGR-3 and melanocytes. The antibody titers of vitiligo patients in live cell ELISA decreased following systemic steroid treatments. Immunoblot analysis demonstrated that 44% of vitiligo sera was directed to melanocyte antigen with a molecular weight of 65 kDa. Inhibition assay using rabbit anti-melanocyte antibody showed inhibition of reaction between vitiligo sera and melanocytes in ELISA and immunoblotting. These findings support the hypothesis that the sera of vitiligo patients have autoantibodies mostly directed to the 65-kDa antigen and this antigen may originate mostly from the melanocyte surface.