EFFECTS OF SOME IMMUNOSUPPRESSIVE PROCEDURES ON MYASTHENIA GRAVIS*

Clinical Observations. A total of 53 MG patients have been treated with different immunosuppressive methods (alone or combined) with the following effects: Thymectomy was performed in 38 patients. The improvement was excellent in 15, and moderate or uncertain in 20. In three patients severe long-lasting deterioration followed the operation. ACTH treatment (n=32): Initial deterioration during the 5-7 days of heavy ACTH treatment (1000 IU) was followed by an improvement lasting on an average 4 months. The improvement was good or moderate in 78% of the patients. Betamethazone treatment has been tried in six patients where ACTH and azathioprine was ineffective. In four of these patients the results were excellent. Azathioprine treatment has been given to 26 patients for periods up to 7 years. An improvement is measurable after 6-12 weeks and it seems maximal after about 1 year. Of the 26, 80% responded favorable with reduction in the need for cholinesterase inhibitors. Severe complications were seen in three patients with one death. Drainage of thoracic duct lymph was initiated in 14 patients up to 4 weeks with rapid improvement lasting as long as drainage was performed. Long-termed effects of the drainage may be present, however. Retransfusion of homologous cell-free lymph precipitated a return of the myasthenic symptoms. Biochemical Studies on Myasthenic Lymph. Using a membrane preparation from the electric organ from Torpedo marmorata and tritiated Naja naja siamensis neurotoxin we demonstrated a decreasing binding of toxin to the receptor in the presence of MG lymph gamma-globulin fraction. Gammaglobulins from controls showed almost no inhibition of the neurotoxin binding. Immunological Studies. An increased frequency of HL-A1 and 8 was found in female patients. LD typing was also performed. During a period of three weeks of thoracic duct drainage 130X10(9) or about 10% of total number of lymphocytes in the body were removed. In the lymph an initial decrease in the proportion of thymus-derived lymphocytes (T cells) occurred, which was accompanied by a sequent increase in the proportion of bone-marrow-derived lymphocytes (B cells). Towards the end of drainage this effect was reverted. Mitogenic stimulation using lymphocytes from thoracic duct drainage revealed no differences as compared to normal cells. The proportions of T and B cells was studied in the peripheral blood in nine patients treated with ACTH. During treatment there was an initial decrease in the proportion of T cells accompanied by a subsequent rise in the proportion of B cells, which was maximal after 3-10 days. These proportions were reverted to normal 1-5 days after the maximal change. The effect of azathioprine on T and B cells has also been studied.