Abstract: Objective To investigate the significance of determining OX40 mRNA and Th1, Th2 of CD3+CD8- T helper lymphocytes in peripheral blood for evaluating renal acute rejection. Methods A total of 40 recipients with renal transplantation and 20 healthy volunteers were enrolled and divided into acute rejection group (n=20) and stable renal allograft function group (n=20) according to the inclusion criteria. The levels of OX40 mRNA in peripheral blood mononuclear cells (PBMCs) were measured by TaqMan real-time reverse transcriptase-polymerase chain reaction (RTPCR) assays. The expression percentages of IFN-γ and IL-4 of CD3+CD8- T lymphocytes (Th1 and Th2) in peripheral blood were determined with flow cytometry. Receiver operating characteristic (ROC) curve was used to evaluate the prediction value. Results The level of OX40 mRNA in PBMCs significantly elevated in acute rejection group compared with that in stable renal allograft function group and normal control group (P＜0.01). There were no significant differences in OX40 mRNA levels between stable renal allograft function group and normal control group (P＞0.05). The expression percentage of Th1 in peripheral blood was significantly higher in acute rejection group compared with that in stable renal allograft function group and normal control group (P＜0.01). No significant difference was found in the expression percentage of Th2 in peripheral blood between the three groups (P＞0.05). The area under ROC curve (AUC) in the diagnosis of acute rejection was 0.903 (95% CI 0.825-0.980) for OX40 mRNA. The AUC of Th1 was 0.731 (95%CI：0.587-0.874). The AUC of combined diagnosis was 0.930 (95% CI: 0.859-1.001). Conclusion The monitoring of OX40 mRNA and Th1 after renal transplantation can predict acute renal allograft rejection.

Key words: renal transplantation, acute rejection, OX40, T helper lymphocytes