Abstract

In the present study, we investigated the effects of FK506 (immunosuppressant, Tacrolimus) on the contents of interferon-gamma (IFN-γ) and interleukin-2 (IL-2), and liver parasite load in mice infected with Toxoplasma gondii (T. Gondii). 120 Kunming mice were intraperitoneally injected with 10²/mouse T. Gondii (RH strain) tachyzoites, and then these mice were randomly divided into FK506 group (group A, 1 mg/kg*d FK506 was intragastrically administrated) and control group (group B, equal volume of normal saline was intragastrically administrated), and there were 30 male and 30 female mice in each group. 2, 4, 6, 7 and 9-day post infection (PI) was carried out; each of 8 mice were randomly sacrificed to harvest peripheral blood and liver samples, and then serum IFN-γ and IL-2 contents and liver parasite loads were detected by ELISA and quantitative fluorescence PCR, respectively. The serum IFN-γ and IL-2 contents of another 8 healthy mice served as normal control values. All mice died within 8 and 10 days after infection in group A and B, respectively. On day 2, 4, 6 and 7 post infection, the serum IFN–γ content in group A was significantly lower than that in group B (p < 0.05). On day 2 post infection, there was no significant difference in serum IL-2 content between groups A and B, but however serum IL-2 content in the group A was lower than that in the group B from day 4 post infection (p < 0.05), and subsequently the difference was more and more significant. On day 4 and 7 post infection, liver parasite loads in the group A was significantly higher than that in the group B (p < 0.01). FK506 plays a regulatory role in T lymphocyte immunity and decrease host immunity, and then risk of T. Gondii infection is also increased.

Key words: Toxoplasma gondii, FK506, animal model, IFN-γ, IL-2.