A transfected human muscle cell line expressing the adult subtype of the human muscle acetylcholine receptor for diagnostic assays in myasthenia gravis.

Immunoprecipitation of human acetylcholine receptor (AChR) is used in the diagnostic assay for myasthenia gravis (MG). We compared human AChR derived from TE671 cells, which express fetal-type AChR, with AChR from TE671-epsilon cells, which we have engineered to express adult-type AChR. Some low-titer MG sera distinguished strikingly between the two subtypes. Four out of seven MG sera that had equivocal titers in standard assays gave positive titers with TE671-epsilon AChR, whereas only one out of seven gave a positive titer with TE671 cells. The new cell line provides a greater concentration of adult AChR than can be obtained from normal human muscle and increases the sensitivity of the diagnostic assay.