Hohlfeld Reinhard, Wekerle Hartmut
Department of Neuroimmunology, Max-Planck Institute of Neurobiology, D-82152 Martinsried, Germany.
J Neuroimmunol. 2008 Sep 15;201-202:21-7. doi: 10.1016/j.jneuroim.2008.05.020. Epub 2008 Jul 21.
The beneficial effects of thymectomy argue for a causal role of the thymus in myasthenia gravis (MG). The MG thymus contains acetylcholine receptor (AChR), which is expressed by myoid cells (whole AChR), and by medullary thymic epithelial cells (AChR subunits). The myoid cells are closely associated with antigen-presenting dendritic cells, helper T cells, and antibody-producing B cells in lymphoid follicles ("lymphofollicular hyperplasia"). Thus, all the cellular components required to initiate and maintain an autoimmune response to AChR are present in the MG thymus. It is unlikely that the cellular alterations in the thymus are secondary to an ongoing peripheral immune response, because they are absent in experimental autoimmune myasthenia gravis.
胸腺切除术的有益效果表明胸腺在重症肌无力（MG）中起因果作用。MG患者的胸腺含有乙酰胆碱受体（AChR），该受体由肌样细胞（完整的AChR）以及髓质胸腺上皮细胞（AChR亚基）表达。肌样细胞与淋巴滤泡中的抗原呈递树突状细胞、辅助性T细胞和产生抗体的B细胞密切相关（“淋巴滤泡增生”）。因此，启动和维持针对AChR的自身免疫反应所需的所有细胞成分都存在于MG患者的胸腺中。胸腺中的细胞改变不太可能是正在进行的外周免疫反应的继发结果，因为在实验性自身免疫性重症肌无力中不存在这些改变。
