Abstract: Objective  To observe the immune response of Th17 cells in mesenteric lymph node （MLN） of C57BL/6 mice infected by Schistosoma japonicum.  Methods  Twenty C57BL/6 mice were randomly divided into infected group and control group each with ten mice. The mice in infected group were infected each with 40±5 S. japonicum cercariae. Five to six weeks later, MLN lymphocytes were separated and stimulated for 4 h by anti-CD3 (1 μg/ml） and anti-CD28 (1 μg/ml） before examination of IL-17 and retinoic acid receptor-related orphan receptor γt(ROR-γt) mRNA by reverse transcription PCR. The level of IL-17 and IFN-γ was detected by ELISA after culturing with supernatant for 72 h. MLN lymphocytes were stimulated for 5 h by 10 ng/ml phorbol myristoyl acetate(PMA) and 1 μg/ml ionomycine. The intracellular cytokines were stained and the content of Th17 and other cytokines was examined by flow cytometry.  Results  The level of IFN-γ ［(214.3±62.6) pg/ml］ and IL-17 [（176.8±62.1) pg/ml] in the supernatant of culured MLN cells from the infected mice was significantly higher than that of normal mice [（46.7±13.9) and 0 pg/ml]（P<0.05）. The expression level of IL-17 and ROR-γt mRNA was also considerably higher than that of normal mice. IL-17+ IL-4+, IL-17+IFN-γ+,  IL-17+ IL-5+ and IL-17+ IL-9 cells accounted for 0.06%, 0.02%, 0.02%， and 0.01% of the mesenteric lymph node CD4+ T cells of the infected mice, respectively. However, IL-17+ IL-10+ and IL-17+ Foxp3+ cells were undetected.  Conclusion  The MLN of S. japonicum-infected C57BL/6 mice can induce the production of Th17 cells, and these cells can secrete IL-4, less IFN-γ, IL-5 and IL-9, but not IL-10, and can not express Foxp3 in the infected mice.

Key words: Schistosoma japonicum, C57BL/6 mouse, Mesenteric lymph node, Th17, Cytokine