Abstract: Objective To explore the expression of PD-1-PD-L pathway of mice immunized with soluble egg antigen （SEA） or soluble male worm antigen （SMWA） of Schistosoma japonicum. Methods Eighteen BALB/c mice were randomly divided into three groups named as control group （A）， SEA immunized group （B） and SMWA immunized group （C）. Mice in groups B and C were subcutaneouly immunized weekly with SEA （50 μg） and SMWA（50 μg） of S. japonicum respectively. After 4 times immunization, the expression of programmed death-1（PD-1）, programmed death-ligand1（PD-L1） and PD-L2 in splenic cells was measured with flow cytometer. The expression of IL-4 and IFN-γ in cu-ltural suspension of splenic cells was detected by sandwich-ELISA after stimulation with ConA. Results The expression ratio of PD-1, PD-L1 and PD-L2 was extremely low in the control group, but increased after the immunization with SEA and SMWA. The expression ratio of PD-1 was （8.24±1.31）% in SEA immunized mice, higher than the mice immunized by SMWA ［（6.08±1.28）%］. PD-L2 was much more elevated in SEA immunized mice ［（5.26±1.73）%］ while PD-L1 more significantly increased with SMWA immunization ［（10.82±2.33）%］. In addition, the up-expression of PD-L1 was associated with the level of IFN-γ and the expression of PD-L2 was associated with IL-4 secretion. Conclusion The expression of PD-1-PDL was up-regulated in BALB/c mice immunized by SEA or SMWA of S. japonicum.

Key words: Schistosoma japonicum, Programmed death-1, Programmed death-ligand, IL-4, IFN-γ