Tomomasa Dan, Nishimura Madoka, Ohya Ayami, Tanita Kay, Wakatsuki Ryosuke, Watanabe Ryohei, Miyamoto Satoshi, Hoshino Akihiro, Kamiya Takahiro, Isoda Takeshi, Kaneko Shuya, Shimizu Masaki, Hijikata Atsushi, Eguchi Katsuhide, Ishimura Masataka, Maeda Yukako, Izawa Kazushi, Meguro Takaaki, Fujimoto Kosuke, Ishikita-Murayama Etsuko, Suzuki Kyogo, Okura Eri, Uehara Tomoko, Takayama Tomotada, Okada Satoshi, Takagi Masatoshi, Morio Tomohiro, Marsh Rebecca A, Kanegane Hirokazu
Department of Pediatrics and Developmental Biology, Institute of Science Tokyo, Tokyo, Japan.
Department of Pediatrics, Graduate School of Medical Sciences Kumamoto University, Kumamoto, Japan.
Clin Exp Immunol. 2025 Jan 21;219(1). doi: 10.1093/cei/uxaf020.
Deficiency of X-linked inhibitor of apoptosis protein (XIAP) is an X-linked recessive inborn error of immunity characterized by abnormal immune responses leading to inflammatory bowel disease and hemophagocytic lymphohistiocytosis. Although XIAP protein expression analysis by flow cytometry (XIAP flow) is commonly used to diagnose XIAP deficiency, certain variants may not affect the protein expression, thereby complicating the diagnostic process. XIAP is crucial for the nucleotide-binding and oligomerization domain 2 (NOD2) signaling pathway. In this study, we aimed to perform a comprehensive analysis of nine patients diagnosed with XIAP deficiency through genetic testing. In addition to XIAP flow, we employed a previously reported method utilizing muramyl dipeptide (MDP) stimulation, a specific agonist of NOD2, to quantitatively evaluate the downstream tumor necrosis factor-alpha (TNFα) production by flow cytometry in patient monocytes (MDP flow). The median mean fluorescence intensity in healthy controls with XIAP flow was 711 (95% confidence interval [CI], 653-815) compared to 195 (95% CI, 161-386) in patients with XIAP deficiency (P < 0.0001). The median percentage of TNFα-producing monocytes in controls with MDP flow was 29.1% (95% CI, 19.6-53.7), while in patients it was 0.34% (95% CI, 0.18-0.82) (P = 0.0008). The receiver operating characteristic curves demonstrated that both XIAP flow and MDP flow exhibited 100% sensitivity and specificity. Taken together, combining XIAP flow and MDP flow analyses allows for a highly accurate diagnosis.
X连锁凋亡抑制蛋白（XIAP）缺乏症是一种X连锁隐性遗传性免疫缺陷病，其特征为异常免疫反应，可导致炎症性肠病和噬血细胞性淋巴组织细胞增生症。尽管通过流式细胞术分析XIAP蛋白表达（XIAP流式分析）常用于诊断XIAP缺乏症，但某些变异可能不影响蛋白表达，从而使诊断过程复杂化。XIAP对核苷酸结合寡聚化结构域2（NOD2）信号通路至关重要。在本研究中，我们旨在对9例经基因检测确诊为XIAP缺乏症的患者进行全面分析。除了XIAP流式分析外，我们还采用了一种先前报道的方法，利用NOD2的特异性激动剂胞壁酰二肽（MDP）刺激，通过流式细胞术定量评估患者单核细胞中下游肿瘤坏死因子-α（TNFα）的产生（MDP流式分析）。XIAP流式分析中健康对照的平均荧光强度中位数为711（95%置信区间[CI]，653-815），而XIAP缺乏症患者为195（95%CI，161-386）（P<0.0001）。MDP流式分析中对照组产生TNFα的单核细胞百分比中位数为29.1%（95%CI，19.6-53.7），而患者为0.34%（95%CI，0.18-0.82）（P=0.0008）。受试者工作特征曲线显示，XIAP流式分析和MDP流式分析均具有100%的敏感性和特异性。综上所述，结合XIAP流式分析和MDP流式分析可实现高度准确的诊断。
