〔Abstract〕 ObjectiveTo investigate the change of interleukin (IL)-18 and Th1, Th2 of CD3 +CD8 -T helper lymphocytes in pediatric liver transplantation with cytomegalovirus (CMV) infection. MethodsA total of 40 pediatric patients who underwent pediatric liver transplantation were collected. Patients were divided into the CMV group ( n= 20) and the non-infected group ( n = 20) according to whether CMV infection occurred. The plasma IL-18 levels were determined by enzyme-linked immunosorbent assay (ELISA). The expression percentage of IFN-γ and IL-10 of CD3 +CD8 -T lymphocytes (Th1 and Th2) in peripheral blood were determined with flow cytometry. ResultsThe expression level of plasma IL-18 significantly increased in the CMV group compared with that in non-infected group ( P< 0.01). The expression percentage of Th1 in peripheral blood significantly decreased in the CMV group compared with that in non-infected group ( P< 0.01). No significant difference was found in the expression percentage of Th2 between CMV group and non-infected group. IL-18 levels were negatively correlated with the Th1 ( P< 0.05). Conclusion The elevated IL-18 levels along with polarized Th 1 subsets’ imbalance involves in the pathogenesis of CMV infection in pediatric liver transplantation.