Changes of splenic interleukin-12p70 concentration in mice infected with Babesia microti and Babesia rodhaini

Interleukin-12 (IL-12) is one of the most important factors for the host’s protective immune response against protozoan infection. To evaluate the effect of bioactive form of IL-12(IL-12p70), expression of IFN-AmRNA and IL-4 mRNA in splenic CD4 positive T cells, anti-parasite delayed type hypersensitivity (DTH), and serum and splenic IL-12p70 concentration were examined in Babesia microti and B. rodhaini infected mice. The expression of IFN-AmRNA as a marker of Th1 cell differentiation was detected in splenic CD4 positive T cells in B. microti infected mice. Activation of DTH response as a marker of cell-mediated immune response was also observed from 2 days after the infection with B. microti, while no response was detected in B. rodhaini infected mice. Serum IL-12p70 was not detected in both B. microti and B. rodhaini infected mice, however, splenic IL-12p70 concentration increased significantly in B. microti infected mice with peaks at 30 hrs and 4 days after the infection. From these results, splenic IL-12p70 increased at 30 hrs after the B. microti infection was considered to closely relate with Th1 cell differentiation followed by cell-mediated immune response in mice