[The significance of determining antibodies to acetylcholine receptor in myasthenia gravis (author's transl)].

: The sera of 65 patients with myasthenia gravis (MG) were analysed for antibodies against the nicotinic acetylcholine receptor (ACh-R) using an immunoprecipitation assay (125I-alpha-bungarotoxin bound to human ACh-R as antigen). In 91% of MG sera elevated antibody titers were found ranging up to 500 times reference values. A control group of 77 patients showing various autoimmunological phenomena had ACh-R antibody concentrations within the reference range. The demonstration of antibodies against ACh-R provides a sensitive and highly specific tool for the diagnosis of MG. In addition, the test is helpful in following patients under treatment with immunosuppressive drugs or plasmapheresis. Antibodies against striated, smooth, or heart muscle (indirect immunofluorescence test) are much less sensitive and nonspecific for the diagnosis of MG.