Mechanism of organophosphorus pesticides-induced inhibition of immune function by using perforin knockout mice.

NK、LAK和CTL主要通过两种机制诱导肿瘤或病毒感染的靶细胞死亡。第一种机制是通过胞吐作用直接释放含有穿孔素、颗粒酶和颗粒酶的细胞溶解颗粒，杀死靶细胞。第二种机制是由Fas配体(Fas- l)/Fas途径介导的。本研究以Fas抗原阳性的YAC-1细胞为靶点，在体外研究了有机磷农药二甲基2,2-二氯酰磷酸（DDVP）对PKO小鼠NK、CTL和LAK活性的影响。我们发现DDVP显著降低NK、CTL和LAK活性呈剂量依赖性，且PKO小鼠的CTL和LAK活性被抗fasl抗体显著阻断，提示DDVP和抗fasl抗体具有相同/相似的抑制LAK和CTL活性的机制。我们进一步发现，DDVP降低了YAC-1细胞上Fas抗原的表达，降低了LAK细胞上FasL的表达，并呈剂量依赖性。综上所述，这些发现表明，ddvp诱导的PKO小鼠NK、LAK和CTL活性的抑制是通过FasL/Fas通路的损伤介导的。我们还发现，DDVP不仅显著抑制颗粒酶的活性，而且通过诱导NK细胞脱粒和抑制穿孔素、颗粒酶A和颗粒酶mRNA的转录来降低细胞内穿孔素、颗粒酶A和颗粒酶的水平。综上所述，这些发现表明，有机磷农药至少通过损害颗粒胞吐和FasL/Fas途径来抑制NK、LAK和CTL活性。我们非常感谢斯坦福大学医学院的Krensky AM教授提供的有益建议。

NK, LAK and CTL induce cell death in tumor or virus-infected target cells by two main mechanisms. The first mechanism is direct release of cytolytic granules that contain perforin, granzymes, and granulysin by exocytosis to kill target cells. The second mechanism is mediated by the Fas ligand (Fas-L)/Fas pathway.In the present syudy, we examined the effect that dimethyl 2,2-dichlorovinyl phosphate (DDVP), an organophosphorus pesticide has on NK, CTL and LAK activities of PKO mice in vitro using the Fas antigen-positive YAC-1 cell as a target. We found that DDVP significantly decreased NK, CTL and LAK activities in a dose-dependent manner, and that the CTL and LAK activities of PKO mice were significantly blocked by anti-FasL antibody, suggesting that DDVP and anti-FasL antibody have the same/similar mechanism of inhibiting LAK and CTL activities. We further found that DDVP decreases the expression of Fas antigen on YAC-1 cells, and the expression of FasL on LAK cells in a dose-dependent manner, respectively. Taken together, these findings indicate that the DDVP-induced inhibition of NK, LAK and CTL activities in PKO mice is mediated by the impairment of the FasL/Fas pathway. We also found that DDVP not only significantly inhibited activities of granzymes, but also decreased the intracellular level of perforin, granzyme A and granulysin, which was mediated by inducing degranulation of NK cells and by inhibiting the transcript of mRNA of perforin, granzyme A and granulysin. Taken together, these findings indicate that organophosphorus pesticides inhibited NK, LAK and CTL activities mediated at least by impairment of both the granule exocytosis and FasL/Fas pathways. We are grateful to Professor Krensky AM at Medical School of Stanford University for his helpful advice.