Long-term immunologic effects of thymectomy in patients with myasthenia gravis

Background: Thymectomy (Tx) is a common therapeutic option to treat myasthenia gravis (MG), but its effects on the immune system are still obscure in humans. Objective: We sought to evaluate long-term immunologic effects of therapeutic Tx in patients with MG. Methods: T- and B-cell subsets and T-cell repertoire were analyzed in 35 patients with MG, 16 with previous Tx (at least 8 years before), 6 with recent (+ and CD8⁺ T cells. They displayed a normal number of total B and CD5⁺ B-circulating lymphocytes, but they also displayed a polyclonal increase in serum IgM and IgG associated with the presence of high levels of a variety of organ- and nonorgan-specific autoantibodies, including anti-dsDNA and anticardiolipin, without clinical evidence of autoimmune disease. These serologic abnormalities were not detectable in both non-Txd and recently Txd patients. After 3 years, 2 long- term Txd patients had systemic lupus erythematosus and an undifferentiated connective tissue disease. Conclusions: The association between MG and laboratory findings of systemic autoimmune disease may be in part related to Tx rather than to MG. Tx may represent a risk for the development of systemic autoimmune disorders over years in patients with MG.