[Immunoadsorption therapy for myasthenia gravis: study on the adsorption capacity of an immunoadsorption column]

Circulating antibodies to the acetylcholine receptor (AchRAb) are detectable in most of the patients with generalized myasthenia gravis (MG). Plasmapheresis has been shown to induce a rapid recovery in company with the decline of the AchRAb titers. Immunoadsorption plasmapheresis (IP) was performed in five patients (three men and two women, mean age 49.6 years) with advanced MG who were refractory to thymectomy and immunosuppressants. Plasmaflo AP 05W was used as a plasma separator and Immusorba TR-350 was used as an immunoadsorption column for plasma perfusion. Each course of treatment consisted of 5 sessions of plasmapheresis on alternate days. Plasma was sampled before and after passage through the adsorption column. We analyzed AchRAb titer in the samples of zero time and sequentially at every 0.5 L of plasma treated. The mean titer of AchRAb in the plasma before passing the adsorption column decreased gradually after every 0.5 L perfused plasma up to 2 L. After perfusion of 2 L plasma, the titer of AchRAb rebounded partly. The mean reduction rate of AchRAb at initial 1 L perfusion of plasma was approximately 100% among sessions of treatment. When the perfusion volume was over 2 L, nearly 50% of AchRAb had not adsorbed through the adsorption column among sessions. The mean titer of AchRAb fell to 74.6%, 52.6%, 43.3%, 35.8%, and 36.5% of the original level after each session of IP. In conclusion, a total of 4 sessions of IP with perfusion of 2 L plasma is an ideal treatment of patients with MG in terms of functional capacity of an immunoadsorption column.