Identifying functional defects in patients with immune dysregulation due to LRBA and CTLA-4 mutations
Identifying functional defects in patients with immune dysregulation due to LRBA and CTLA-4 mutations
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DOI：
10.1182/blood-2016-10-745174
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发表时间：
2017-03-16
期刊：
影响因子：
20.3
通讯作者：
Sansom, David M.
中科院分区：
文献类型：
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作者：
Hou, Tie Zheng;Verma, Nisha;Sansom, David M.
杂合子CTLA-4缺陷已被报道为具有免疫失调特征的常见可变免疫缺陷的单基因原因。CTLA-4的直接突变导致调节性T细胞（Treg）功能缺陷，这与控制CTLA-4配体、CD 80和CD 86水平的能力受损有关.然而，影响CTLA-4途径的其他突变，如最近报道的LRBA突变，间接影响CTLA-4表达，导致临床上类似的疾病。因此，需要对CTLA-4途径缺陷敏感的稳健表型分析方法来了解此类免疫失调综合征。在这里，我们描述了能够区分CTLA-4途径中的各种缺陷的测定。当将分析限制在CD 45 RA（-）Foxp 3（+）部分时，发现评估总CTLA-4表达水平是最佳的。刺激后的CTLA-4诱导和溶酶体阻断化合物的使用将CTLA-4与LRBA突变区分开。短期T细胞刺激提高了区分Foxp 3（+）Treg区室的能力，清楚地揭示了这些病症中的Treg扩增。最后，我们开发了一种功能导向的测定方法来测量CTLA-4的配体摄取，CTLA-4对配体结合或转运突变敏感，否则难以检测，并且适合于测试CTLA-4途径基因中的新突变。这些方法很可能是有价值的解释突变的功能意义的CTLA-4途径中确定的基因测序方法。
Heterozygous CTLA-4 deficiency has been reported as a monogenic cause of common variable immune deficiency with features of immune dysregulation. Direct mutation in CTLA-4 leads to defective regulatory T- cell (Treg) function associated with impaired ability to control levels of the CTLA-4 ligands, CD80 and CD86. However, additional mutations affecting the CTLA-4 pathway, such as those recently reported for LRBA, indirectly affect CTLA-4 expression, resulting in clinically similar disorders. Robust phenotyping approaches sensitive to defects in the CTLA-4 pathway are therefore required to inform understanding of such immune dysregulation syndromes. Here, we describe assays capable of distinguishing a variety of defects in the CTLA-4 pathway. Assessing total CTLA-4 expression levels was found to be optimal when restricting analysis to the CD45RA(-)Foxp3(+) fraction. CTLA-4 induction following stimulation, and the use of lysosomal- blocking compounds, distinguished CTLA-4 from LRBA mutations. Short-term T- cell stimulation improved the capacity for discriminating the Foxp3(+) Treg compartment, clearly revealing Treg expansions in these disorders. Finally, we developed a functionally orientated assay to measure ligand uptake by CTLA-4, which is sensitive to ligand-binding or-trafficking mutations, that would otherwise be difficult to detect and that is appropriate for testing novel mutations in CTLA-4 pathway genes. These approaches are likely to be of value in interpreting the functional significance of mutations in the CTLA-4 pathway identified by gene-sequencing approaches.