A practical enzyme immunoassay for anti-acetylcholine receptor antibodies in myasthenia gravis

A practical enzyme immunoassay (EIA) has been developed for the measurement of anti-acetylcholine receptor (AChR) antibodies in sera from patients with myasthenia gravis (MG). This system is based on the double antibody technique, using denervated rat muscle AChR labeled with horseradish peroxidase-linked alpha-bungarotoxin (HRP-alpha BGT). This method has the following advantages compared to conventional radioimmunoassay (RIA): (1) HRP-alpha BGT is more stable than [125I]alpha BGT and can be used for at least one year without any loss of the binding activity to AChR and enzymatic activity, (2) the procedure avoids the use of radioactive isotopes, and (3) the equipment for our EIA is more economical than that for RIA.