Plasmapheresis in myasthenia gravis.

The discovery of pathogenic autoantibody of acetylcholine receptor (AChR) in the sera of patients with myasthenia gravis (MG) laid the foundation for attempting to control the disease process by removing anti-AChR antibody with plasmapheresis and reducing its rate of reaccumulation with immunosuppressive drug therapy. Plasmapheresis alone may have a favorable short-term impact in MG, and has been successfully used as a temporary measure prethymectomy, in MG crisis, and while awaiting another therapy to produce benefit. Used as a primary therapy in MG, plasmapheresis has been effective in producing stable clinical improvement and reduction of anti-AChR antibody titers only when combined with immunosuppressive drugs and administered ina protracted series of weekly, large-volume exchanges. Prednisone combined with azathioprine has been a generally effective immunosuppressive drug regimen with plasmapheresis, but neither drug by itself appears to be capable of producing stable improvement in conjunction with plasmapheresis. Cyclophosphamide, chlorambucil and vincristine also show therapeutic promise when used with plasmapheresis is selected patients. The long-term reductions in titer of antibody to AChR in MG patients attaining stable improvement indicates that cytotoxic chemotherapeutic agents may act together with prednisone under the conditions of plasmapheresis to reduce the populations of lymphoid clones with specificity for AChR.