Division of Rheumatology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan.
Semin Hematol. 2013 Jan;50 Suppl 1:S43-9. doi: 10.1053/j.seminhematol.2013.03.018.
Regulatory T cells characterized by CD4, CD25, and transcription factor forkhead box P3, called Tregs, are a subpopulation of CD4(+) T cells specialized for immune suppression. Tregs contribute to maintenance of peripheral immune tolerance, and their defects are thought to play a role in the pathogenesis of various autoimmune diseases. Immune thrombocytopenia (ITP) is an autoimmune disease characterized by increased platelet destruction and reduced platelet production, resulting in decreased platelet count. Recently, a series of studies in adults and children with ITP have found that the frequency of Tregs is reduced in circulation, bone marrow, and spleen, and Treg function is impaired. Treg dysregulation is improved after platelet count is recovered by treatment with dexamethasone, rituximab, or thrombopoietin receptor agonists. In addition, a critical role of Tregs in preventing the anti-platelet autoimmune response has been demonstrated in mice deficient in functional Tregs. Thrombocytopenia observed in Treg-deficient mice is mediated through production of IgG anti-platelet autoantibodies, which is analogous to human ITP. Further studies evaluating mechanisms of Treg dysregulation in ITP patients are necessary to elucidate the pathogenesis of ITP and develop novel therapeutic strategies that suppress anti-platelet autoimmune response.
调节性 T 细胞（Regulatory T cells）是 CD4+T 细胞的一个亚群，其特征为表达 CD4、CD25 和转录因子叉头框蛋白 P3（forkhead box P3），称为 Tregs。Tregs 具有免疫抑制作用，有助于维持外周免疫耐受。其功能缺陷被认为在多种自身免疫性疾病的发病机制中起作用。免疫性血小板减少症（immune thrombocytopenia，ITP）是一种自身免疫性疾病，其特征为血小板破坏增加和血小板生成减少，导致血小板计数降低。最近，一系列关于成人和儿童 ITP 的研究发现，循环、骨髓和脾脏中的 Treg 频率降低，Treg 功能受损。用地塞米松、利妥昔单抗或血小板生成素受体激动剂治疗使血小板计数恢复后，Treg 失调得到改善。此外，在缺乏功能性 Tregs 的小鼠中，Tregs 在防止抗血小板自身免疫反应中发挥了关键作用。Treg 缺陷小鼠中观察到的血小板减少是通过产生 IgG 抗血小板自身抗体介导的，类似于人类 ITP。进一步研究 Tregs 在 ITP 患者中失调的机制对于阐明 ITP 的发病机制和开发抑制抗血小板自身免疫反应的新治疗策略是必要的。
