Initial Studies on the Role of Hydatid Fluid in the Immune Evasion Strategies of Echinococcus granulosus

Modulation of the immune response is an important strategy in hosts chronically infected with Echinococcus granulosus, which modulates the response of the host immune system for long periods of time. The induction of NK cell function might be a considerable component of this infection. This study explores the modulation of NK cells and T lymphocytes by hydatid cyst fluid in vitro. Splenocytes from BALB/c mice were treated with hydatid fluid. After 72 h of exposure to the fluid, NK cell cytotoxicity and the expression of NKG2D on NK cells were reduced. In the co-culture system, hydatid cyst fluid also modulated CD4(+)CD25(+) T cell differentiation and enhanced splenocyte secretion of TGF-beta. In conclusion, hydatid fluid (HF) can stimulate the differentiation of T lymphocytes into Treg cells and induce the secretion of TGF-beta, which could be involved in the suppression of NK cell-mediated cytotoxicity and the reduction of NKG2D receptor expression. The potential role of hydatid fluid in the regulation of the innate immune response of the host to hydatid cysts is discussed.