Polyclonal B-cell activity in myasthenia gravis.

Using a protein A-reverse hemolytic plaque assay, we found that some patients with myasthenia gravis have increased numbers of circulating immunoglobulin secreting cells (IgSC). This pattern was not related to drug therapy, age, sex, duration of symptoms, thymectomy, or serum levels of AChR antibody, although elevated IgSC values tended to occur in patients with active symptoms. The responses of peripheral blood mononuclear cells to pokeweed mitogen were normal. These data suggest increased in vivo polyclonal B-cell activation in some myasthenic patients, although in vitro polyclonal B-cell activation is normal.