A New Assay Method for Anti-Acetylcholine Receptor (AChR) Antibodies in Sera from Patients with Myasthenia Gravis Using Anti-Torpedo californica AChR Antibody

抄録

We have developed a sensitive immunoprecipitation (IP) assay that uses anti-Torpedo californica (Tc) acetylcholine receptor (AChR) antibody for measuring anti-AChR antibodies in sera from patients with myasthenia gravis (MG). With this assay, we simultaneously detected two types of anti-AChR antibodies in MG sera: enhancing-type antibodies that accelerate the binding of anti-Tc AChR antibody to human AChR and blocking-type antibodies that inhibit the binding of α-bungarotoxin to AChR. Antibodies were detected in 80% of the MG sera, 45% being the enhancing- and 35% the blocking-type antibodies. The inhibitory activities of these blocking-type antibodies correlated well with the titers of blocking-type antibodies obtained by the Concanavalin A assay. The titers of the enhancing-type antibodies also were correlated with those of non-blocking-type antibodies ass measured by the standard IP assay.