The pathogenesis of myasthenia gravis--a hypothesis.

We have suggested that a thymic factor plays a critical role in the pathogenesis of myasthenia gravis. The presence of specific ACh R antibodies in more than 90% of patients with myasthenia gravis has provided us with a marker for this disorder and has greatly increased our understanding of the pathophysiology. These antibodies can induce physiological parameters similar to those seen in myasthenia gravis following passive transfer to experimental animals and can accelerate degradation of ACh R in myotube culture. However, clinical studies suggest that additional factors of thymic origin are necessary for the development of the clinical features of myasthenia gravis. While the nature of the thymic factor(s) is speculative, this hypothesis has a significant clinical implication as it argues for an early, total thymectomy as the treatment of choice for myasthenia gravis.