Rowe Alexander M, Brundage Kathleen M, Barnett John B
Department of Microbiology, Immunology and Cell Biology, West Virginia University, Morgantown, WV 26506, USA.
Toxicol Appl Pharmacol. 2007 Jun 1;221(2):179-88. doi: 10.1016/j.taap.2007.01.012. Epub 2007 Feb 7.
The herbicide atrazine is a known immunotoxicant and an inhibitor of human natural killer (NK) cell lytic function. The precise changes in NK cell lytic function following atrazine exposure have not been fully elucidated. The current study identifies the point at which atrazine exerts its affect on the stepwise process of human NK cell-mediated lyses of the K562 target cell line. Using intracellular staining of human peripheral blood lymphocytes, it was determined that a 24-h in vitro exposure to atrazine did not decrease the level of NK cell lytic proteins granzyme A, granzyme B or perforin. Thus, it was hypothesized that atrazine exposure was inhibiting the ability of the NK cells to bind to the target cell and subsequently inhibit the release of lytic protein from the NK cell. To test this hypothesis, flow cytometry and fluorescent microscopy were employed to analyze NK cell-target cell co-cultures following atrazine exposure. These assays demonstrated no significant decrease in the level of target cell binding. However, the levels of NK intracellular lytic protein retained and the amount of lytic protein released were assessed following a 4-h incubation with K562 target cells. The relative level of intracellular lytic protein was 25-50% higher, and the amount of lytic protein released was 55-65% less in atrazine-treated cells than vehicle-treated cells following incubation with the target cells. These results indicate that ATR exposure inhibits the ability of NK cells to lyse target cells by blocking lytic granule release without affecting the ability of the NK cell to form stable conjugates with target cells.
除草剂阿特拉津是一种已知的免疫毒性物质，也是人类自然杀伤（NK）细胞裂解功能的抑制剂。阿特拉津暴露后NK细胞裂解功能的具体变化尚未完全阐明。当前研究确定了阿特拉津对人类NK细胞介导的K562靶细胞系裂解的逐步过程产生影响的关键点。通过对人外周血淋巴细胞进行细胞内染色，确定体外24小时暴露于阿特拉津不会降低NK细胞裂解蛋白颗粒酶A、颗粒酶B或穿孔素的水平。因此，推测阿特拉津暴露抑制了NK细胞与靶细胞结合的能力，进而抑制了NK细胞裂解蛋白的释放。为了验证这一假设，采用流式细胞术和荧光显微镜分析阿特拉津暴露后的NK细胞-靶细胞共培养物。这些检测表明靶细胞结合水平没有显著降低。然而，在与K562靶细胞孵育4小时后，评估了NK细胞内保留的裂解蛋白水平和释放的裂解蛋白量。与用载体处理的细胞与靶细胞孵育后相比，阿特拉津处理的细胞内裂解蛋白的相对水平高25 - 50%，释放的裂解蛋白量少55 - 65%。这些结果表明，阿特拉津暴露通过阻断裂解颗粒的释放抑制了NK细胞裂解靶细胞的能力，而不影响NK细胞与靶细胞形成稳定共轭物的能力。
