Anti-acetylcholine antibodies and the pathogenesis of myasthenia gravis

Using an ELISA system, antibodies recognizing conjugated acetylcholine (ACh) were detected in sera of patients suffering from myasthenia gravis. The mean antibody level was three times higher in sera from myasthenic than from control patients. No correlation was found between anti-ACh antibody levels and anti-ACh receptor (AChR) titer. Also, the anti-ACh antibody titers were independent of sex and age of patients. Competition experiments demonstrated that the most immunoreactive compounds were choline-glutaryl-bovine serum albumin (BSA) and choline-succinyl-BSA. Antibodies present in the sera of myasthenic patients recognized an antigenic determinant mimicking conjugated ACh. The antibody affinity and specificity were sufficiently high for the detection of ACh in locust brain.