Complement-dependent lysis of cultured rat myotubes by myasthenic immunoglobulins.
We used cultured myotubes to demonstrate complement-dependent lysis of muscle membranes by serum from patients with myasthenia gravis. Lysis was monitored by light microscopy and release of incorporated [86Rb]. In the presence of guinea pig complement (GPC), 18 of 37 heat-inactivated myasthenic sera (49%), but none of 16 controls, caused morphologically detectable myotube lysis. Ten of 19 myasthenic sera (53%) increased [86Rb]-release compared with 10 controls. Immunoglobulin fractions retained the complement-dependent lytic activity. Inactivation of GPC prevented the lysis. [86Rb]-release appeared to correlate with clinical severity. The complement-dependent lysis resulted in a decrease in the number of acetylcholine receptors (AChRs) in myotubes, and AChR-immunoglobulin complexes were found in the medium of lysed cultures. The data suggest that cultured myotubes can be used to document complement-dependent antibody reactions in the pathogenesis of myasthenia.
D000328:Adult; D000818:Animals; D002462:Cell Membrane / Q000276:immunology; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000032:analysis*; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000276:immunology*; D009157:Myasthenia Gravis / Q000276:immunology*; D051381:Rats; D011919:Rats, Inbred Strains; D011950:Receptors, Cholinergic / Q000032:analysis
D011950:Receptors, Cholinergic; D003165:Complement System Proteins