去甲基化处理对NK-92MI细胞杀伤活力的影响

Effect of Demethylating Treatment on Cytotoxicity of NK-92MI Cells

为观察DNA去甲基化处理对NK细胞系NK-92MI细胞抑制性KIR表达及细胞杀伤活力的影响,探讨抑制性kir基因去甲基化与NK细胞功能之间的可能联系,采用甲基化抑制剂5-氮胞苷处理NK-92MI细胞,采用流式细胞术检测NK-92MI细胞表面KIR3DL1、KIR2DL2/KIR2DL3、KIR2DL1表达及细胞活力,并采用流式细胞仪将NK-92MI细胞分选为KIR3DL1阳性和KIR3DL1阴性细胞群,采用乳酸脱氢酶释放法检测NK-92MI细胞对白血病细胞系K562的杀伤活力。结果显示:应用终浓度为1.0、2.5和5μmol/L的5-氮胞苷作用72小时可以诱导NK-92MI细胞KIR3DL1、KIR2DL2/KIR2DL3、KIR2DL1表达增加,同时NK-92MI对K562细胞的杀伤活力降低,5-氮胞苷在1-5μmol/L范围内不影响NK-92MI的细胞活力,KIR3DL1阳性NK-92MI细胞的杀伤活力较KIR3DL1阴性细胞的杀伤活力低。结论:去甲基化处理通过诱导抑制性KIR表达增加抑制NK-92MI细胞的杀伤活力。

In order to investigate the effect of demethylating treatment on the expression of inhibitory KIR and the cytolytic activity of NK-92MI cells, and to study the possible relationship between the demethylation of inhibitory kir gene and the function of NK cells. NK-92MI cells were treated with 5-azacytidine to induce DNA demethylation. The expression of KIR3DL1, KIR2DL2/KIR2DL3, KIR2DL1 and the viability of NK-92MI ceils were detected by flow cytometry. The KIR3DL1 positive and the KIR3DL1 negative NK-92MI cells were also sorted by flow cytometry. The cytotoxicity of NK-92MI against K562 cells was detected by the LDH release assay. The results demonstrated that the expressions of KIR3DL1, KIR2DL2/KIR2DL3 and KIR2DL1 in NK-92MI cells all increased after treating with 1.0, 2.5 and 5 μmol/L of 5-azacytidine for 72 hours. And the cytotoxicity of NK-92MI against K562 cells decreased. In these dose range, 5-azacytidine did not influence the viability of NK-92MI cells. Additionally, the cytotoxicity of KIR3DL1 positive NK-92MI cells was lower than that of the K/R3DLI negative cells. It is concluded that the demethylating treatment suppresses the cytotoxicity of NK-92MI cells through increasing the expression of inhibitory KIR.