探讨长期监测T细胞亚群绝对计数水平对肾移植受者术后感染的预警作用。

回顾性分析2017年1月至2021年5月在上海交通大学医学院附属瑞金医院26例行肾移植术后新发感染受者临床资料(感染组，感染发生在移植后1～240个月)。选择129例同期肾移植术后无感染、健康受者作为对照组。感染组连续或定期测量外周血T细胞亚群CD3^＋、CD4^＋和CD8^＋绝对计数，并与对照组检测数据进行比较。根据移植后采样时间将感染组和对照组各分为6个亚组，分析感染亚组与其相应对照亚组之间T细胞亚群绝对计数的差异。正态分布计量资料采用两独立样本t检验和单因素方差分析比较，非正态分布计量资料采用Mann-Whitney U检验比较，计数资料采用χ²检验比较。使用受试者工作特征(ROC)曲线分析T细胞亚群绝对计数在肾移植术后预警感染性疾病的最优值。P<0.05为差异有统计学意义。

感染组和对照组受者CD4^＋/CD8^＋比值分别为(1.2±0.5)、(1.3±0.6)，差异无统计学意义(t＝0.610，P>0.05)。感染组受者CD3^＋、CD4^＋和CD8^＋ T细胞绝对计数[(367±212)、(189±117)和(161±92)个/μL]均低于对照组[(1 374±663)、(695±334)和(626±377)个/μL]，差异均有统计学意义(t＝14.036、13.541和12.311，P均<0.05)。CD3^＋、CD4^＋和CD8^＋ T细胞绝对计数在6个感染亚组受者中差异均无统计学意义(P均>0.05)。对照亚组1受者CD3^＋、CD4^＋和CD8^＋ T细胞绝对计数均低于对照亚组5，差异均有统计学意义(P均<0.05)。CD4^＋、CD8^＋和CD3^＋绝对计数预测肾移植术后感染性疾病最优截断值分别为712、362和255个/μL，敏感度分别为94.6%、92.2%和96.1%，特异度分别为92.3%、96.2%和88.5%。

肾移植受者低T细胞亚群绝对计数水平具有预示及预警感染风险的作用。

To investigate the kinetics of T cell subsets absolute counts as a long-term monitoring tool during infections.

The clinical data of 26 kidney transplant recipients (KTRs), transplanted at Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, with newly diagnosed infection from January 2017 to May 2021 were retrospectively analyzed (infection group, infections occurred between 1 month and 240 months post-transplant). A total of 129 healthy KTRs without infection from matching post-transplant periods were selected as a control group. T cell subsets CD3⁺ , CD4⁺ , and CD8⁺ absolute counts in peripheral blood were continuously or periodically measured in the infected group, and then compared with the data of the control group. Afterward, the infected and control groups were each further split into 6 subgroups according to the sampling time post-transplant. Then we analyzed the kinetics of T cell subsets absolute counts between each control subgroups, and the difference between each infected subgroup and their corresponding control subgroup. Normally distributed data were compared using two independent samples t-test and one-way ANOVA. Non-normally distributed data were compared using Mann-Whitney U test. Nominal data were compared using χ² test. Receiver operating characteristic (ROC) curves were used to analyze the optimal cut-off value of absolute T cell subset counts in determining patients at risk of infectious diseases following renal transplantation. P<0.05 was considered statistically significant.

No difference was found between the CD4⁺ /CD8⁺ ratio of the infected group (1.2±0.5) and that of the control group (1.3±0.6) (t=0.610, P>0.05). The CD3⁺ , CD4⁺ , and CD8⁺ T cells absolute counts of the infected group were significantly lower than those of the control group [(367±212), (189±117), and (161±92) cells/μL vs (1, 374±663), (695±334), and (626±377) cells/μL, respectively] (t=14.036, 13.541 and 12.311, all P values<0.05). No significant difference was found in the CD3⁺ , CD4⁺ , and CD8⁺ T cells absolute counts across the 6 subgroups of the infected group (all P values >0.05). However, the CD3⁺ , CD4⁺ , and CD8⁺ T cells absolute counts of the control subgroup 1 were lower than those of the control subgroup 5 (all P values <0.05). The best cut-off values of CD4⁺ , CD8⁺ , and CD3⁺ determined from the ROC curves analysis in this patient population were 712, 362, and 255 cells/μL, with a sensitivity of 94.6%, 92.2%, and 96.1%, and specificity of 92.3%, 96.2%, and 88.5%, respectively.

Low T cell subsets absolute counts may be regarded as a potential risk factor for developing opportunistic infections and a biomarker with meaningful predictive value.