Division of Immunology and Allergy, Canadian Centre for Primary Immunodeficiency, Jeffrey Modell Research Laboratory for the diagnosis of Primary Immunodeficiency, Hospital for Sick Children, Toronto, Ontario, Canada.
J Allergy Clin Immunol. 2010 Dec;126(6):1226-33.e1. doi: 10.1016/j.jaci.2010.07.029.
ζ-associated protein, 70 kd (ZAP70), deficiency in human subjects results in a combined immunodeficiency characterized by normal numbers of circulating CD4 T cells and CD8 lymphocytopenia. Patients who live beyond infancy can also experience autoimmune manifestations.
We sought to further characterize the nature of the T-cell populations found in ZAP70-deficient patients and explored the mechanisms that might predispose them to autoimmunity.
T-cell development was assessed by examining T-cell receptor (TCR) gene rearrangements and thymopoiesis by measuring TCR exclusion circle levels. TCR repertoire on CD4 and CD8 T-cell populations was assessed by means of flow cytometry. T-cell gene expression patterns were examined by means of exonic microarray analysis and apoptotic responses by means of Annexin V binding and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling.
Cells displaying recombination events from all stages of TCR gene rearrangement were present in the peripheral blood of ZAP70-deficient patients; however, the late TCRD-deleting rearrangement was significantly reduced. TCR exclusion circle levels were also found to be low. Surprisingly, all Vβ families were detected in both CD4(+) and CD8(+) circulating T cells. Several Vβ families were significantly overrepresented, which is reminiscent of autoimmune disorders. Levels of mRNA for cytotoxic T lymphocyte-associated antigen 4, TGF-β, and IL-10 were found to be low, a signature of autoimmunity. Finally, Fas-mediated CD4 T-cell apoptosis was found to be reduced in vitro, and staining of thymus biopsy specimens revealed reduced thymocyte apoptosis.
We show that in the absence of ZAP70, thymopoiesis is altered and differentiation to double-positive cells is hampered. Circulating T cells appear poorly regulated, do not differentiate into T(H)2 T cells, lack a number of inhibitory growth controls, and display reduced apoptosis, all predisposing patients to exaggerated inflammation and autoimmunity.
ζ 相关蛋白，70 kd（ZAP70），在人类中的缺陷导致一种联合免疫缺陷，其特征是循环 CD4 T 细胞和 CD8 淋巴细胞减少。能够存活到婴儿期之后的患者也可能经历自身免疫表现。
我们试图进一步描述 ZAP70 缺陷患者中发现的 T 细胞群体的性质，并探讨可能使他们易患自身免疫的机制。
通过检查 T 细胞受体（TCR）基因重排来评估 T 细胞发育，并通过测量 TCR 排除环水平来评估胸腺发生。通过流式细胞术评估 CD4 和 CD8 T 细胞群体上的 TCR 库。通过外显子微阵列分析检查 T 细胞基因表达模式，并通过 Annexin V 结合和末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记法检查凋亡反应。
ZAP70 缺陷患者外周血中存在显示 TCR 基因重排所有阶段重组事件的细胞；然而，晚期 TCRD 删除重排明显减少。TCR 排除环水平也发现较低。令人惊讶的是，所有 Vβ 家族均在 CD4(+)和 CD8(+)循环 T 细胞中检测到。几个 Vβ 家族被显著过度表达，这类似于自身免疫疾病。细胞毒性 T 淋巴细胞相关抗原 4、TGF-β 和 IL-10 的 mRNA 水平较低，这是自身免疫的特征。最后，体外发现 Fas 介导的 CD4 T 细胞凋亡减少，并且胸腺活检标本染色显示胸腺细胞凋亡减少。
我们表明，在没有 ZAP70 的情况下，胸腺发生改变，并且双阳性细胞的分化受到阻碍。循环 T 细胞似乎调节不良，不能分化为 T(H)2 T 细胞，缺乏许多抑制生长的控制，并且显示出减少的凋亡，所有这些都使患者易发生过度炎症和自身免疫。
