吲哚胺2,3-双加氧酶在急性髓系白血病细胞株的表达及其活性调节的实验研究

Expression and Activity Regulation of Indoleamine 2,3-Dioxygenase in Acute Myeloid Leukemia Cells

目的:研究吲哚胺2,3-双加氧酶(IDO)在急性髓系白血病细胞株(AML)的表达及其活性调节。方法:采用RT-PCR检测经γ-干扰素(IFN-γ)、胸腺肽α1(Tα1)、IFN-γ+Tα1及氯喹等药物作用前后HL-60细胞株及K562细胞株IDO mRNA及Toll样受体9(TLR9)mRNA表达变化;采用考马斯亮蓝染色法及改良比色法检测经IFN-γ、Tα1、IFN-γ+Tα1作用前后两细胞株IDO酶活性变化。结果:两细胞株均表达IDO mRNA及TLR9 mRNA;细胞经IFN-γ作用后,IDO mRNA表达及酶活性增加并呈浓度依赖性;经Tα1作用后,IDO mRNA表达及酶活性降低并呈浓度依赖性;经IFN-γ+Tα1共同作用后,Tα1明显削弱IFN-γ对IDO mRNA表达及酶活性的上调作用(P<0.01);经氯喹作用后,两细胞株IDO mRNA表达无明显变化;经IFN-γ、Tα1、IFN-γ+Tα1及氯喹等药物作用后,两细胞株TLR9 mRNA表达无明显变化。结论:AML细胞表达IDO mRNA且具有酶活性,IDO可能在AML细胞诱导机体产生免疫耐受过程中起关键作用,可作为判断白血病预后的新指标;Tα1下调IDO表达及酶活性,并可削弱IFN-γ对IDO的诱导作用,提示Tα1作为免疫调节剂可能成为AML免疫治疗的新手段。

Objective：To investigate the expression and activity regulation of indoleamine 2,3-dioxygenase（IDO） in acute myeloid leukemia cells.Methods：Expression of IDO and TLR9 in HL-60 and K562 cells cocultured with or without IFN-γ,Tα1,IFN-γ ＋ Tα1 and chloroquine were determined by reverse transcription-polymerase chain reaction（RT-PCR）.Then,the IDO activity in HL-60 and K562 cells cocultured with or without IFN-γ,Tα1,IFN-γ ＋ Tα1 was assayed by coomassie brilliant blue staining and modified colorimetric method.Results：Both IDO and TLR9 mRNA were expressed in HL-60 and K562 cells;IFN-γ increased the expression and activity of IDO in a concentrationdependent manner;Tα1 decreased the expression and activity of IDO in a concentration-dependent manner;the upregulation of IFN-γ on IDO induced expression and activity had been weakened by Tal（P 〈0.01）;Chloroquine had no effect on the expression of IDO.The expression of TLR9 in HL-60 cells and K562 cells cocultured with IFN-γ,Tα1,IFN-γ ＋ Tα1 and chloroquine was not significantly changed.Conclusion：IDO can be expressed in acute myeloid leukemia cells and possesses the activity.IDO may play an important role in immune tolerance induced by leukemia cells,and become a new predictor of AML prognosis.Tal decreases the expression and activity of IDO,which can weaken the induction of IFN-γ on IDO expression and activity,thus Tal as an immune modulator may be a new agent for AML immunotherapy.