Effect of myasthenic patients' immunoglobulin on acetylcholine receptor turnover: selectivity of degradation process.

Publisher Website
Google Scholar
Abstract
Antibodies [Ab] in the sera of patients with myasthenia gravis probably play an important role in the pathogenesis of the disorder. They accelerate the degradation of acetylcholine receptors in cultured mammalian skeletal muscle and at intact neuromuscular junctions. To elucidate the mechanism of the A-accelerated degradation process, cultures were prepared in which 1 set of acetylcholine receptors was exposed to myasthenic immunoglobulin [Ig] while a 2nd set of acetylcholine receptors, newly incorporated after exposure to the Ig, was not. The set of acetylcholine receptors with bound myasthenic Ig was degraded at 2-3 times the normal rate, while the 2nd set of acetylcholine receptors without bound Ig was degraded at the control rate. This suggests that the binding of Ab from myasthenic patients alters the acetylcholine receptors in some way that causes them to be selected for preferential degradation by the muscle cells. New synthesis, and incorporation of the acetylcholine receptors into the surface membrane of cultured skeletal muscle was unaffected by exposure to myasthenic Ig.