Nicotinic acetylcholine receptor mRNAs in myasthenic thymuses: association with intrathymic pathogenesis of myasthenia gravis.

Reverse transcription and the polymerase chain reaction showed that the alpha-, beta- and gamma-subunit genes of nicotinic acetylcholine receptor (AChR) in human skeletal muscle were expressed in myasthenia gravis (MG) thymuses (3 thymomas and 7 hyperplastic thymuses). A study of the expression of these subunit mRNAs in a variety of human tissues showed that alpha-subunit mRNA was expressed in human thymus and cerebral cortex, and that all three subunits were expressed only in human child thymus. Our results suggest that a complete AChR similar to extrajunctional (embryonic) muscle AChR is expressed in MG thymuses and that intrathymic AChR might be the primary antigen which induces autoimmune responses to muscle AChR.