探讨重症甲型流感儿童淋巴细胞亚群特点，并评价其在重症甲型流感中的诊断价值。

回顾性研究2018年10月至2019年12月首都医科大学附属北京地坛医院收治的病程在48 h以内的甲型流感住院患儿共129例，按照年龄、性别进行1∶2配对，仅有发热、上呼吸道症状者为轻症组（43例）；有持续高热> 3 d，合并肺炎、呼吸困难、神志改变等为重症组（86例）。检测两组患儿血常规、淋巴细胞亚群，比较两组患儿上述指标的差异。应用受试者工作特征曲线（ROC）分析淋巴细胞亚群在重症甲型流感中的诊断效能，并应用Medcalc软件对各指标曲线下面积（AUC）进行两两比较。

与轻症组相比，重症甲型流感患儿淋巴细胞计数[1 554（928，2 605）个/μl vs. 2 723（1 792，4 108）个/μl]、T细胞计数[728（419，1 491）个/μl vs. 1 558（1 123，2 259）个/μl]，CD4⁺ T细胞计数[418（237，699）个/μl vs. 1558（1 123，2 259）个/μl]均显著下降，差异有统计学意义（Z = -3.959、-2.833、-4.399，P < 0.001、0.005、< 0.001）。CD4⁺ T细胞计数诊断甲型流感灵敏度和特异度分别为60.4%和95.5%，AUC为0.825（95%CI：0.715~0.905）。CD4⁺ T细胞计数与CD8⁺ T细胞计数、NK细胞计数、B细胞计数的AUC差异均有统计学意义（Z = 1.961，2.227，2.602，P = 0.0498、0.026、0.0093），与淋巴细胞计数、T细胞计数AUC差异无统计学意义（Z = 1.016、1.372，P = 0.310、0.17）。

重症甲型流感患儿病程初期存在细胞免疫功能受损，病程48 h内CD4⁺ T细胞计数对于重症甲型流感有较好的诊断效能。

To investigate the characteristics of lymphocyte subsets in children with severe influenza A, and to evaluate their diagnostic value for children with severe influenza A.

A retrospective study was conducted on 129 hospitalized children with influenza A within 48 hours in Beijing Ditan Hospital, Capital Medical University from October 2018 to December 2019. A 1∶2 match was made according to age and sex. Only those with fever and upper respiratory symptoms were classified as mild group (43 cases); those with persistent high fever > 3 days, and those with pneumonia, dyspnea and altered consciousness were classified as severe group (86 cases). Blood routine examination and lymphocyte subsets of the two groups were detected and compared. The diagnostic efficacy of each parameter of lymphocyte subsets in severe influenza A were analyzed by receiver operating characteristic curve (ROC), while the area under the curve (AUC) of each parameter were compared in pairs by Medcalc software.

Lymphocyte count [1 554 (928, 2 605) cells/μl vs. 2 723 (1 792, 4 108) cells/μl] and T cell count [728 (419, 1 491) cells/μl vs. 1 558 (1 123, 2 259) cells/μl], CD4⁺ T cell count [418 (237, 699) cells/μl vs. 1 558 (1 123, 2 259) cells/μl] decreased, all with significant differences (Z =-3.959, -2.833, -4.399; P < 0.001, 0.005, < 0.001). The sensitivity and specificity of CD4⁺ T cell count were 60.4% and 95.5%, the area under the curve (AUC) was 0.825 (95%CI: 0.715-0.905). The AUC of CD4⁺ T cell count compared with that of CD8⁺ T cell count, NK cell count and B cell count were all with significantly difference (Z = 1.961, 2.227, 2.602; P = 0.0498, 0.026, 0.0093), but without significantly difference compared with lymphocyte count and T cell count (Z = 1.016, 1.372; P = 0.310, 0.17).

The cellular immune function of children with severe influenza A is impaired at early stage of the disease. CD4⁺ T cell count within 48 hours of the disease has good diagnostic efficacy for severe influenza A.