Dynamics of CD4~+CD25~+ regulatory T cells of mice infected with Schistosoma japonicum and reversal of function

Objective To investigate the dynamics of CD4+CD25+ regulatory T cells of mice infected with Schistosoma japonicum and ascertain factors that could reverse the inhibition of CD4+CD25+ regulatory T cells.Methods Mice were infected with cercaria of S.japonicum and the dynamics of CD4+CD25+ regulatory T cells of these mice were examined in different stages of infection using a fluorescence-activated cell sorter(FACS);the polarization of the immune response was monitored by measuring serum cytokines using enzyme-linked immunosorbent assay(ELISA).The spleen CD4+CD25+ regulatory T cells of infected mice were isolated with a magnetic microbead system.Two oligo-nucleotide fragments(CpG1-ODN,CpG2-ODN) were synthesized,and a lymphocyte proliferation test was used to screen for those that reversed the inhibition of CD4+CD25+ regulatory T cells.Results The data on FACS of CD4+CD25+ regulatory T cells in different stages of infection showed that the levels of CD4+CD25+ regulatory T cells in peripheral blood and the spleens of mice increased gradually as the schistosome infection developed.The immune response of mice was Th2-polarized with elevated serum IL-5 and decreased IFN-γ.CpG2-ODN stimulated the lymphocytes to proliferate effectively and reversed the immunosuppressive action of CD4+CD25+ regulatory T cells in a lymphocyte proliferation test.Conclusion When mice were infected with S.japonicum,the levels of CD4+CD25+ T regulatory cells in peripheral blood and the spleen increased gradually and immune response was Th2-polarized.CpG2-ODN reversed the immunosupression of CD4+CD25+ T regulatory cells.