Molecular aspects of experimental autoimmune myasthenia gravis

Structure and function studies on acetylcholine receptor (AChR) were attained by studying various derivatives of the receptor molecule, by analysis of monoclonal antibodies, and by investigating the possible structural relationship between AChR and the thymus. Pharmacologically inactive denatured AChR preparation does not induce myasthenia in rabbits, although it elicits antibodies that cross-react with the intact receptor. Denatured AChR has both preventive and therapeutic effects on experimental autoimmune myasthenia gravis. Mild tryptic digestion of AChR does not abolish the pharmacological specificity and myasthenic activity of the receptor. Trypsinated AChR, which on SDS gel electrophoresis shows one major band with a molecular weight of 27,000, represents an active receptor derivative with a relatively low structural complexity. Monoclonal antibodies against defined determinants of AChR were elicited and characterized. One monoclonal antibody line is directed against the cholinergic binding site. Experiments demonstrating that thymic lymphocytes bear a surface antigen that cross-reacts with AChR are described.