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 microg/ml) and anti-CD28 (1 microg/ml) before examination of IL-17 and retinoic acid receptor-related orphan receptor gammat (ROR-gammat) mRNA by reverse transcription PCR. The level of IL-17 and IFN-gamma was detected by ELISA after culturing with supernatant for 72h. MLN lymphocytes were stimulated for 5h by 10 ng/ml phorbol myristoyl acetate (PMA) and 1 microg/ml ionomycin. The intracellular cytokines were stained and the content of Th17 and other cytokines was examined by flow cytometry.
Results: The level of IFN-gamma [(214.3 +/- 62.6) pg/ml] and IL-17 [(176.8 +/- 62.1) pg/ml] in the supernatant of cultured MLN cells from the infected mice was significantly higher than that of normal mice [(467 +/- 13.9) and 0 pg/ml) (P < 0.05). The expression level of IL-17 and ROR-gammat mRNA was also considerably higher than that of normal mice. IL-17+ IL-4+, IL-17+ IFN-gamma+, 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-gamma, IL-5 and IL-9, but not IL-10, and can not express Foxp3 in the infected mice.