Safety, stability, and effectiveness of immunoadsorption under membrane plasmapheresis treatment for myasthenia gravis. Nine patients (five women and four men, average age 50.4 years) with refractory myasthenia gravis (MG) underwent thymectomy and were then treated with immunoadsorption under membrane plasmaphersis (IAP). Thymic histology showed hyperplasia in nine patients. An immunoadsorption column (ASAHI, Med, Co) was made with tryptophan. A Plasouto 1,000 (ASAHI, Med, Co) was used as the machine. The plasma separator was a first filter (ASAHI, Med, Co), and immunoadsorption columns were used for plasma perfusion. IAP treatment was performed three times weekly for a total of six times, after which IAP was done every 3 weeks. The removal rate of anti-Ach-R titer was 54 +/- 12%; IgG, IgA, and IgM levels improved in nine of nine patients after IAP treatment, and improvement of gait disturbances were seen in two of two. Muscle strength improved in all nine patients, whereas speech disturbances improved in two of three. Eye ptosis improved in nine of nine patients. Subjective improvement was reported by nine of nine patients, and none had severe side effects with IAP. In conclusion, IAP is a safe, stable, effective, and clinically useful treatment. for MG. 