Acetylcholine receptor antibody and clinical response to thymectomy in myasthenia gravis.

We studied serum anti-acetylcholine receptor (AChR) antibody and clinical response to thymectomy in myasthenia gravis for 1 to 3 1/2 years postoperatively in 25 patients who did not receive immunosuppressive drugs. Clinical grade was assessed "blind." Mean final anti-AChR values were significantly reduced compared with thymectomy values (69.6 +/- 7.5% SEM; p less than 0.05). Anti-AChR fell steadily to 42-15% in the six patients who developed remission. Overall, there was a significant correlation between changes in anti-AChR and in clinical grade at 1 year (p less than 0.01) and at final assessment (p less than 0.001). An association between fall in anti-AChR and clinical improvement was absent in five individuals and not accounted for by change in antibody characteristics.