THE SPECTRUM OF AUTOANTIBODIES IN MYASTHENIA-GRAVIS

Patients with myasthenia gravis (MG) produce a wide spectrum of autoantibodies against AChR and other muscular autoantigens. These autoantibodies are heterogeneous with respect to functional effects, antigen specificity, isotype, and fine specificity. This explains why the antibody titers correlate only relatively loosely with the clinical severity of the disease. The radio-immunoprecipitation assay for the determination of anti-AChR antibodies is a very sensitive and specific test. However, in laboratories not experienced with the test, unreliable results have been obtained. Besides anti-AChR autoantibodies, anti-striational autoantibodies are clinically important. These antibodies, which are directed against myosin, actinin and titin, are found in about a third of patients with generalized MG, and in 80-90% of patients with MG and thymoma. Like anti-AChR antibodies, anti-striational autoantibodies are heterogeneous.