Supplementary Material for: Successful Cord Blood Transplantation for Idiopathic CD4⁺ Lymphocytopenia

Idiopathic CD4⁺ lymphocytopenia (ICL) is the depletion of CD4⁺ lymphocytes to &lt;300 cells/mm³ without human immunodeficiency virus infection or other causes of lymphocytopenia. ICL causes fatal infections; its etiology remains unclear and it lacks consensus regarding therapeutic options. We report the first patient with ICL who had a successful clinical course following a cord blood transplant (CBT). A 45-year-old woman was diagnosed with ICL and underwent partial hepatectomy for an abscess caused by the <i>Mycobacterium avium</i> complex. No specific gene alterations were detected through next generation sequencing-based evaluation. Following a reduced-intensity conditioning (RIC) regimen consisting of fludarabine, busulfan, and 4 Gy total body irradiation, a single-unit CBT was performed. Neutrophils were engrafted on day +14. CD4⁺ lymphocyte counts increased to over 300 cells/mm³ on day +436. After 75 months, she was alive without any sequelae. CBT with an RIC regimen could be a curable treatment option for ICL.特发性CD4+淋巴细胞减少症（Idiopathic CD4+ lymphocytopenia, ICL）指未感染人类免疫缺陷病毒（human immunodeficiency virus, HIV），亦无其他可导致淋巴细胞减少的诱因时，CD4+淋巴细胞计数降至300个/mm³以下的病症。ICL可引发致命性感染，其病因尚未明确，且治疗方案尚无共识。本文报告首例经脐带血移植（cord blood transplant, CBT）后获得良好临床转归的ICL患者：一名45岁女性被诊断为ICL，因鸟分枝杆菌复合群（Mycobacterium avium complex）感染引发脓肿接受了部分肝切除术；经基于下一代测序（next generation sequencing, NGS）的评估未检测到特异性基因改变。患者接受了由氟达拉滨、白消安及4Gy全身照射组成的减低强度预处理（reduced-intensity conditioning, RIC）方案，随后实施单份脐带血移植。患者于移植后+14天实现中性粒细胞植入，+436天时CD4+淋巴细胞计数升至300个/mm³以上。随访75个月后，患者仍存活且无任何后遗症。本案例提示，采用减低强度预处理方案的脐带血移植或可成为ICL的可治愈治疗选择。