[Demonstration of acetylcholine receptor antibodies in the serum of myasthenia gravis patients applying affinity chromatographically purified human acetylcholine receptor preparations (author's transl)].

Sera from 75 patients with Myasthenia gravis were tested for acetylcholine receptor antibodies using acetylcholine receptors from human skeletal muscle. From the crude Triton x-100 extract, which has so far been used for antibody tracing, a pure acetylcholine receptor preparation was obtained by affinity chromatography using alpha-Najatoxin-Sepharose 4B. When the purified 125J-alpha-Bungarotoxin-acetylcholine receptor complex was applied in a radioimmunoassay 80% of the Myasthenia gravis patients had acetylcholine receptor antibodies in contrast to none of the tested control persons. Inspite of using a pure acetylcholine receptor preparation, no clear-cut correlation was found between the amount of serum acetylcholine receptor antibodies and the clinical stage of the disease. When individual antibody titration curves were established, different reaction patterns were observed indicating either different antibody specificities in regard to antigenic determinants on the receptor molecule or differences in the antibody affinity.