Increased binding of anti-acetylcholine receptor antibodies to thymic antigen in patients with myasthenia gravis and other autoimmune diseases, as compared to those with myasthenia gravis alone.

We compared the binding activity against acetylcholine receptors solubilized from human muscle (AChRM) and human thymus (AChRT), of sera from patients with myasthenia gravis (MG) alone, to those of sera from patients with myasthenia gravis and associated autoimmune diseases (MG AD). The sera of the MG AD group bound relatively better to thymic antigen (86% vs. 62%). This group was found to contain a higher proportion of women over 40 years of age (more than 50% of the group). The expression of a particular AChR antigen in normal human thymus may be one of the factors involved in the pathogenesis of MG, especially when this disease is associated with other autoimmune disorders.