New antigen for antibody detection in myasthenia gravis.

We assayed anti-acetylcholine receptor (AChR) antibodies in 61 myasthenic patients using human and fetal calf muscle AChR as antigen. Anti-AChR antibodies were detected in 85% of patients with human AChR and in 80% with fetal calf AChR. In 27 patients, the titers detected with fetal calf AChR were higher than those obtained with human AChR. Titers with different fetal calf AChR preparations were reproducible. Fetal calf AChR is a suitable antigen for immunologic analysis of myasthenic patients.