腺苷脱氨酶缺陷重症联合免疫缺陷伴疫苗接种后播散性水痘感染一例

Adenosine deaminase deficiency associated severe combined immunodeficiency with disseminated varicella infection after vaccination, a case report

目的提高对腺苷脱氨酶（ADA）缺陷重症联合免疫缺陷（SCID）及疫苗接种后播散性水痘感染的认识。方法结合1例ADA缺陷SCID伴疫苗接种后播散性水痘感染的临床资料和文献复习，探讨ADA缺陷SCID背景知识、临床表现、诊断和治疗。结果患儿存在生长停滞情况，以发热、皮疹3周余入院，出皮疹前两周曾接种水痘疫苗，水痘直接免疫荧光试验阳性，血液常规检查淋巴细胞比例和绝对值（105×10^6／L）明显降低，IgG（1520mg／L）、IgM（250mg／L）和IgA（102mg／L）显著降低，淋巴细胞亚群CD3、CIM、CD8和CD19的相对比例和绝对值均显著降低，CD56比例升高，但其绝对值显著降低。红细胞ADA值明显降低，脱氧核苷酸腺苷明显升高。结论ADA缺陷SCID存在特征性改变，目前的治疗方法包括造血干细胞移植、酶替代治疗和基因治疗。对生长发育停滞儿童需重视免疫功能评估，对免疫缺陷病患儿需加强疫苗接种管理。

Objective To enhance the knowledge of adenosine deaminase （ADA） deficiency associated severe combined immunodeficiency （SCID） with disseminated varicella infection after vaccination. Methods With case report and review of literature, the background knowledge, clinical and laboratory findings, diagnosis and treatment of ADA-deficient SCID were discussed. Results The patient had the condition with failure to thrive. The main complaint was more than three weeks of fever and rash. He had received the live attenuated Oka strain varicella vaccination approximately two weeks before the onset of rash. Varicella infection was confirmed with direct immunofluorescence assay. The patient had mild leukopenia, with 3% lymphocytes. The initial immunologic workup included decreased IgG, IgM and IgA, abnormal expanded lymphocyte enumeration which confirmed the reduction of CD3, CD4, CD8, CD19 and CD56. Enzyme testing for ADA activity showed remarkably low level in the hemolysate, as well as increased levels of deoxyadenosine nucleotides. Conclusion ADA-deficient SCID has some characteristic clinical and laboratory findings. Management options for ADA-deficient SCID include hematopoietic stem cell transplantation, enzyme replacement therapy and gene therapy. Immunodeficiency should be considered in children with severe failure-to-thrive. Live vaccine administration should be avoided in patients with immunodeficiency.