Effects of myasthenia gravis patient sera on human myoblast cultures

Abstract

To investigate the role of acetylcholine receptor (AChR) and other anti-muscle autoantibodies in myasthenia gravis (MG). Since many of these autoantibodies target proteins with structural or signalling functions, we examined the effect of MG sera on muscle cell morphology. Primary human myoblast cultures were exposed to MG sera and morphological changes observed by light and fluorescence microscopy. MG patient sera caused changes in cell shape (cell retraction) and led to the formation of inclusion bodies and intracellular vesicles. A disordered arrangement of actin microfilaments was also observed. The effects were not complement-mediated, were both dose- and time-dependent, and appeared to correlate with disease severity of the MG donor. The factors responsible for these effects in vitro may also play a role in the pathogenesis of MG in vivo. Further study of these factors may improve our understanding of MG pathogenesis.