人类白细胞抗原G及其受体在肾移植术后监测的临床意义

Applications of monitoring human leukocyte antigen G and its inhibitory receptors in post-renal transplantation

目的 探讨人类白细胞抗原G（HLA-G）作为判断肾移植预后的生物标记物的价值并分析HLA-G受体的表达与HLA-G作用机制的相关性.方法 选取2006年2月至2008年6月解放军第三○九医院全军器官移植中心施行初次肾移植受者215例,根据术后临床状况分为肾功稳定组（n=173）和急性排斥组（n=42）,采集外周血用酶联免疫吸附试验（ELISA）法检测可溶性人类白细胞抗原G5（sHLA-G5）表达含量,流式细胞术分析HLA-G受体免疫球蛋白样受体2（ILT-2）在T、B淋巴细胞的表达及杀伤细胞免疫球蛋白样受体（KIR）2DL4在自然杀伤（NK）细胞的表达.采用受试者工作特征（ROC）曲线运算sHLA-G5阈值,预测肾移植术后排斥反应.运用回归分析验证sHLA-G5与急性排斥反应发生的相关性.结果 sHLA-G5水平预测急性排斥反应组的最适域值为139.0μg/L,其敏感度为63.6%,特异度为82.1%,曲线下面积（AUC）为0.780.二元Logistic回归分析显示sHLA-G5是肾移植术后急性排斥反应发生的独立影响因素（P=0.019,OR=0.039,95%可信区间为2.091～5.661）.急性排斥组CD4＋T细胞、CD8＋T细胞、B细胞表面的ILT-2表达均低于肾功稳定组（21%±7%比52%±17%,23%±6%比39%±16%,21%±7%比39%±16%,均P＜0.05）.急性排斥组NK细胞表面的KIR2DLA表达也低于肾功稳定组（31%±10%比57%±21%,P＜0.05）.结论 sHLA-G5表达水平对预测肾移植术后排斥反应具有较高的敏感度和特异度,HLA-G诱导免疫耐受的机制可能与淋巴细胞表面ILT-2、KIR2DLA的高表达密切相关.

Objective To study the feasibility of human lecocyte antigen-G （HLA-G） as a posttransplantation prognostic biomarker and discuss the correlation of its receptor expression and the mechanisms. Methods A total of 215 recipients in our centre from February 2006 to June 2008 were divided into stable kidney function group （n = 173） and acute rejection group （n = 42）. The soluble human lecocyte antigen-G5 （sHLA-GS） level in peripheral plasma was detected by ELISA. And the HLA-G receptor ILT-2, KIR2DL4 on T, B, NK lymphocytes were analyzed by flow cytometry （FCM）. The sHLA-G5 cutoff level by ROC curve was employed to predict the events of acute post-transplantation rejection. And regression analysis was used to determine the association of sHLA-G5 with acute rejection. Results An optimal cutoff value of 139.0 μg/L could be defined for sHLA-G5 （sensitivity： 63.6%, specificity： 82. 1%, AUC：0. 780）. Binary regression analysis showed that sHLA-G5 played an independent role on acute rejection （P=0.019, OR=0.039, 95%CI：2.091 -5.661）. The rate of HLA-G receptor ILT-2 on CD4＋T cell,CD8 ＋T cell and B cell in acute rejection group was statistically lower than that in stable kidney function group （21% ±7% vs52% ±17%, 23% ±6% vs 39% ±16%, 21% ±7% vs 39% ±16%, all P〈0. 05）. The expression of KIR2DL4 on NK cells in acute rejection group was statistically lower than that in stable kidney function group （31% ± 10%vs 57% ±21% ,P 〈0. 05）. Conclusion sHLA-G5 level may be predicted for acute rejection with a high sensitivity and specificity. The up-regulated expression of ILT-2 and KIR2DLT may contribute to immunology tolerance in peripheral circulation.