The immunologic role of thymectomy in the treatment of myasthenia gravis: Implication of thymus-associated B-lymphocyte subset in reduction of the anti-acetylcholine receptor antibody titer

Meinoshin Okumura, Mitsunori Ohta, Yukiyasu Takeuchi, Hiroyuki Shiono, Masayoshi Inoue, Kenjiro Fukuhara, Yoshihisa Kadota, Shinichiro Miyoshi, Yoshitaka Fujii, Hikaru Matsuda, Steven J. Mentzer, Ross M. Bremner

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Abstract

Background and Purpose: Thymectomy is generally accepted as the major option of treatment for myasthenia gravis. To elucidate the biological role of thymectomy in the treatment of myasthenia gravis, the immunologic characteristics of the thymus was studied in association with the postoperative kinetics of the anti-acetylcholine receptor antibody titer. Materials and Methods: Thirty-four patients with nonthymomatous myasthenia gravis who had positive anti-acetylcholine receptor antibody titer and undergoing extended thymectomy were subjected to the study. Reduction of anti-acetylcholine receptor antibody titer was evaluated in terms of the proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy to that before the operation. The numbers of B lymphocytes (CD19+ cells) and the germinal center B lymphocytes (CD19+CD38high cells) present in 1 g of the thymic tissue were calculated by flow cytometry. Results: The proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy ranged from 27.5% to 150%. The numbers of B lymphocytes and the germinal center B lymphocytes in 1 g of the thymic tissue ranged from 0.19 × 106/g to 162.8 × 106/g and from 0.09 × 106/g to 33.4 × 106/g, respectively. The proportion of anti-acetylcholine receptor antibody titer at 1 year after thymectomy had a significant inverted correlation with the number of B lymphocytes (P = .002) as well as that of the germinal center B lymphocytes (P = .007). Conclusion: Effectiveness of thymectomy was dependent on predominance of B lymphocytes and the germinal center B lymphocytes in the thymus, suggesting that one of the biological roles of thymectomy in the treatment of myasthenia gravis is removing the thymus-associated germinal centers.

Original languageEnglish
Pages (from-to)1922-1928
Number of pages7
JournalJournal of Thoracic and Cardiovascular Surgery
Volume126
Issue number6
DOIs
Publication statusPublished - Dec 2003

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine

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    Okumura, M., Ohta, M., Takeuchi, Y., Shiono, H., Inoue, M., Fukuhara, K., Kadota, Y., Miyoshi, S., Fujii, Y., Matsuda, H., Mentzer, S. J., & Bremner, R. M. (2003). The immunologic role of thymectomy in the treatment of myasthenia gravis: Implication of thymus-associated B-lymphocyte subset in reduction of the anti-acetylcholine receptor antibody titer. Journal of Thoracic and Cardiovascular Surgery, 126(6), 1922-1928. https://doi.org/10.1016/S0022-5223(03)00938-3