Beta-arrestin and arrestin are recognized by autoantibodies in sera from multiple sclerosis patients

Multiple sclerosis (MS), one of the most common chronic neurologic diseases, is characterized by the presence of multiple plaques of demyelination throughout the central nervous system. Although the etiology of the disease has not been established, it is believed to involve autoimmune mechanisms. We have examined sera from patients with MS for the presence of antibodies to antigens from brain and retina. Immunoblot analysis of soluble fraction of proteins from bovine brain revealed a prominent band at 45 kDa stained with sera of 8-14 patients with MS. In two patients with MS, serum antibody titers during relapse were higher compared with those when the patients were in remission. These antibodies were undetectable in cerebrospinal fluid of our MS patients and additionally were absent in sera of patients with other neurological diseases and normal control subjects. Furthermore, immunoblot analysis of the soluble fraction from bovine retinal rod outer segments revealed a prominent protein band at 48 kDa stained with MS sera. This antigen was purified to homogeneity from bovine retinal outer segments and identified as arrestin. Additionally, sera from MS patients reacted with purified beta-arrestin 1, a 45-kDa protein homologous to arrestin that is found in various tissues. Using limited proteolysis of arrestin and a competitive ELISA test with a synthetic peptide, we identified the recognition site(s) for antibodies in sera of MS patients at a dominant immunogenic site on arrestin located at the C-terminal region of the molecule. We suggest that the presence of circulating antibodies reactive with beta-arrestin or arrestin may be related to the course of MS progression.