AUTOIMMUNE-DISEASES AGAINST CELL-SURFACE RECEPTORS - MYASTHENIA-GRAVIS, A PROTOTYPE ANTIRECEPTOR DISEASE

Autoimmune diseases against cell surface receptors are the result of a mainly antibody-mediated attack on membrane receptors. This results i n a hypofunction of the target organ; occasionally antibodies can exer t an agonist effect, e.g. in Graves' disease. Myasthenia gravis (MG) i s an autoimmune disease of the neuromuscular junction associated with a plethora of other diseases, mainly autoimmune diseases. Antibodies a gainst the acetylcholine receptor (AChR) reduce the number of receptor s necessary for efficient neuromuscular transmission. The effector mec hanisms of MG can be studied elegantly in an experimental animal model in rodents immunized with AChR or injected with antibodies against AC hR. The thymus is thought to play a central role in the induction of M G. Microscopic analysis of these thymuses revealed a follicular hyperp lasia of the medulla or a lympho-epithelial thymoma. Thymectomy result s in clinical improvement along with a decline in anti-AChR antibody t itres. Additional therapeutic measures include anticholinesterase drug s, immunosuppression and plasmapheresis.