Antibodies against myofibrillar proteins in myasthenia gravis patients

Antibodies against various myofibrillar proteins were measured by enzyme-linked immunosorbent assay (ELISA) in sera of thirty-one myasthenic patients. The antibody activity expressed as optical absorbance values was higher in 15 (48%) patients for myosin, 10 (32%) patients for tropomyosin, 9 (29%) patients for troponin, 7 (23%) patients for alpha-actinin, and 1 (3%) patient for actin as compared with 95% tolerance limits of eleven normal individuals. Twenty-five (81%) of the patients had one of these antibodies or more. Anti-myosin antibody titer was higher in male patients (0.447 +/- 0.196; mean +/- SD, p less than 0.05) than in female patients (0.316 +/- 0.107), and positively correlated with the age of onset of myasthenia gravis (r = 0.41, p less than 0.05). Anti-tropomyosin antibody titers had an inverse correlation with the age of onset (r = -0.46, p less than 0.01). No significant correlation was found between the antibody activities and other clinical conditions, including the severity and duration of disease, and treatments (systemic treatment with corticosteroids or previous thymectomy). Positive correlations were observed between anti-myosin antibody and anti-troponin antibody titers (r = 0.44, p less than 0.02), and between anti-actin antibody and anti-alpha-actin in antibody titers (r = 0.39, p less than 0.05), but no significant correlation between other pairs of antibodies against myofibrillar proteins was found.(ABSTRACT TRUNCATED AT 250 WORDS)