Acquired myasthenia gravis: what we have learned from experimental and spontaneous animal models

Acquired myasthenia gravis (MG) is a disorder of neuromuscular transmission in which muscle weakness results from an autoantibody mediated depletion o f acetylcholine receptors (AChR) at the neuromuscular junction. Experimenta l autoimmune myasthenia gravis, described in rodents and rabbits, has provi ded a good model of the effects of the autoimmune response against AChR and has shown that the specificities of the immune response in MG are those th at would be obtained by immunization with native AChR. It has provided litt le information, however, about what initiates and sustains the immune respo nse in MG. Acquired MG occurs spontaneously in dogs and may be the most com mon neuromuscular disorder that can be diagnosed in this species. As in hum an MG, an autoimmune response against AChR has been demonstrated and AChR a utoantibodies have been implicated in the pathogenesis. The variability in clinical presentation, methods of diagnosis, and occurrence with other auto immune diseases and neoplasia are identical to that of humans. Future studi es of spontaneous canine autoimmune MG may provide clues to the determinati on of what factors initiate and sustain the autoimmune response to AChR, an d in the study of specific suppression of the autoimmune response against A ChR. (C) 1999 Elsevier Science B.V. All rights reserved.