[Up-expression of PD-1-PD-L induced by immunization with SEA and SMWA of Schistosoma japonicum in mice].

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 subcutaneously immunized weekly with SEA (50 microg) and SMWA (50 microg) 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-gamma in cultural 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-gamma 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.