流式细胞术在肾移植术后感染中的诊断价值

目的  探讨流式细胞术在肾移植术后感染中的诊断价值。方法  根据术后影像学和实验室检查结果，将51例首次肾移植受体分为细菌组33例、真菌组9例、BK病毒组9例；另选择肾移植术后稳定的受体28例作为稳定组。采用流式细胞术分析各组受体外周血淋巴细胞亚群比例和绝对计数。比较各组肾移植受体的肾功能、外周血淋巴细胞亚群的比例及绝对计数；采用受试者工作特征（ROC）曲线分析淋巴细胞亚群比例和绝对计数在肾移植术后感染性疾病中的诊断价值。结果  与稳定组相比，细菌组、真菌组和BK病毒组血清肌酐（Scr）水平和血尿素氮（BUN）水平均有不同程度升高，差异均有统计学意义（P=0.035、0.007、0.024；0.037、0.006、0.032）。与稳定组比较，细菌组和真菌组CD16⁺CD56⁺自然杀伤（NK）细胞比例均下降（P=0.036、0.015）；真菌组CD4⁺/CD8⁺T细胞比例明显下降（P=0.004）。与细菌组相比，真菌组和BK病毒组的CD3⁺CD8⁺T细胞比例均升高（P=0.013、0.008），CD3⁺CD4⁺T细胞比例均降低（P=0.003、0.010），CD4⁺/CD8⁺T细胞比例均明显下降（P=0.003、0.005）。与稳定组比较，细菌组、真菌组、BK病毒组CD3⁺T细胞数量、CD3⁺CD8⁺T细胞数量、CD16⁺CD56⁺NK细胞数量均明显降低（P=0.025、0.002、0.003；0.015、0.005、0.006；0.001、0.001、0.031）；真菌组和BK病毒组CD3⁺CD4⁺T细胞数量降低（P=0.001、0.003）；BK病毒组CD19⁺B细胞数量明显降低（P=0.019）。与细菌组比较，真菌组CD3⁺CD4⁺T细胞数量明显降低（P=0.023）。ROC曲线分析显示，CD3⁺CD4⁺T细胞和CD16⁺CD56⁺NK细胞数量诊断真菌感染的准确度较高，ROC曲线下面积分别为0.8492和0.8889；CD3⁺T细胞、CD3⁺CD4⁺T细胞和CD19⁺B细胞数量诊断BK病毒感染的准确度较高，ROC曲线下面积分别为0.8472、0.8452和0.8115。结论  采用流式细胞术检测外周血淋巴细胞亚群可以评估患者机体免疫功能状态，绝对计数能够直观地判断免疫程度，两者结合对于肾移植受者感染性疾病的诊断和鉴别诊断具有指导意义。

Diagnostic value of flow cytometry in postoperative infection after renal transplantation

Objective To assess the value of flow cytometry in the diagnosis of postoperative infection following renal transplantation. Methods According to postoperative imaging findings and laboratory examination outcomes, 51 recipients undergoing the first renal transplantation were divided into the bacteria (n=33), fungus (n=9) and BK virus (n=9) groups. Twenty-eight recipients with stable conditions after renal transplantation were assigned into the stable group. Flow cytometry was adopted to detect the percentage and absolute counting of lymphocyte subpopulation in the peripheral blood of recipients in each group. Renal function, percentage and absolute counting of lymphocyte subpopulation in the peripheral blood were statistically compared among different groups. Receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic value of the percentage and absolute counting of lymphocyte subpopulation in infectious diseases after renal transplantation. Results Compared with the stable group, the serum creatinine (Scr) and blood urea nitrogen (BUN) levels in the bacteria, fungus and BK virus groups were significantly up-regulated, respectively (P=0.035, 0.007, 0.024; 0.037, 0.006, 0.032). Compared with the stable group, the percentage of CD16+ CD56+ natural killer (NK) cells was significantly declined in the bacterial (P=0.036) and fungus groups (P=0.015), and the proportion of CD4+ /CD8+T cells was dramatically decreased in the fungus group (P=0.004). Compared with the bacterial group, the percentage of CD3+ CD8+T cells was significantly elevated (P=0.013 and 0.008), the proportion of CD3+ CD4+T cells was considerably declined (P=0.003 and 0.010), and the percentage of CD4+/CD8+T cells was significantly declined (P=0.003 and 0.005) in the fungus and BK virus groups. Compared with the stable group, the quantity of CD3+ T cells, CD3+ CD8+T cells and CD16+ CD56+ NK cells was significantly declined in the bacterial, fungus and BK virus groups, respectively (P=0.025, 0.002, 0.003; 0.015, 0.005, 0.006; 0.001, 0.001, 0.031). In addition, the quantity of CD3+ CD4+T cells was considerably decreased in the fungus and BK virus groups (P=0.001, 0.003). The quantity of CD19+ B cells was significantly reduced in the BK virus group (P=0.019). Compared with the bacterial group, the quantity of CD3+ CD4+T cells was considerably lower in the fungus group (P=0.023). ROC curve analysis revealed that the quantity of CD3+ CD4+T cells [area under curve(AUC)=0.8492] and CD16+ CD56+ NK cells (AUC=0.8889) yielded relatively high accuracy in the diagnosis of fungal infection. The quantity of CD3+ T cells (AUC=0.8472), CD3+ CD4+T cells (AUC=0.8452) and CD19+ B cells (AUC=0.8115) yielded relatively high accuracy in the diagnosis of BK virus infection. Conclusions Flow cytometry detection of the lymphocyte subpopulation in peripheral blood can evaluate the immune function of patients. Absolute counting of lymphocyte subpopulation can directly assess the degree of immunity. These two combined parameters provide guiding significance for the diagnosis and differential diagnosis of infectious diseases in recipients after renal transplantation.