Role of innate immune cells in protection against Toxoplasma gondii at inflamed site

The intraperitoneal infection with Toxoplasma gondii (T. gondii) caused accumulation of γδ T, NK, NK1.1+T-like (NKT) cells at inflamed sites. To clarify the roles of these cells in protection against T. gondii at the inflamed sites, BALB/c mice were depleted of γδ T, NK, NK and NKT cells by treatment with antibody against TCR-γδ, asialoGM1 or Interleukin-2 receptor β-chain (IL-2Rβ), respectively, prior to infection. Mice treated with anti-TCR-γδ monoclonal antibody (mAb) became more susceptible to infection, whereas mice treated with anti-IL-2Rβ mAb acquired resistance. Treatment with anti-asialoGM1 Ab showed no effect. We previously reported that heat shock protein 65 (HSP65) in macrophages induced by γδ T cells plays an essential role in protective immunity against T. gondii infection, by preventing apoptotic death of infected macrophages. In the present study, we showed that treatment with anti-IL-2Rβ mAb, but not with anti-asialoGM1 Ab, enhanced the HSP65 induction in macrophages, and inhibited Interleukin-4 (IL-4) expression in nonadherent peritoneal exudate cells. Furthermore, neutralization of endogenous IL-4 by anti-IL-4 mAb enhanced the HSP65 induction in macrophages. These findings suggest that NKT cells, but not NK cells, negatively regulate the protective immunity against T. gondii infection possibly by producing IL-4and suppressing HSP65 induction.

データ元 : http://medical.med.tokushima-u.ac.jp/jmi/