Characterization of acetylcholine receptor antibodies in a patient with primary biliary cirrhosis.

Antibodies against the acetylcholine receptor were found in a patient with primary biliary cirrhosis. The patient had no clinical or electrophysiological evidence of disturbed neuromuscular function. The antibodies were of both IgG and IgM isotype. Following passive transfer, these antibodies showed the same capacity to bind in vivo to mouse muscle receptors as immunoglobulins from patients with myasthenia gravis. The affinity of the antibodies was high and comparable to that found in myasthenia gravis patients.