干扰素γ诱导人肝癌细胞表达HLA-E逃避NK细胞杀伤

IFN-γ induced human hepatocarcinomal cells expressing HLA-E gene to escape from NK cytotoxicity

目的探讨干扰素γ(IFN-γ)诱导人肝癌细胞表达非经典人类白细胞抗原HLA-E,及对NK细胞肿瘤杀伤的影响。方法用不同终浓度的IFN-γ分别体外持续诱导人肝癌细胞系(BEL-7402)72h。用细胞免疫组织化学、Western-blot、逆转录PCR和流式细胞技术,检测各组细胞HLA-E基因产物的表达及各组的NK细胞杀伤率。结果与空白对照相比,IFN-γ(浓度100～1000U/ml)诱导BEL-7402细胞表达HLA-E基因产物(抗原、mRNA和蛋白)明显增多(P<0.01),细胞表面HLA-E抗原相应增多(P<0.01)。细胞表达HLA-E基因的强弱与IFN-γ诱导浓度有关。高浓度IFN-γ(500～1000U/ml)诱导细胞HLA-E阳性率、表达强度高于低浓度诱导(100～400U/ml)。最适宜的IFN-γ浓度为500U/ml,高浓度组的NK细胞杀伤率更低(P<0.01)。结论高浓度IFN-γ(500～1000U/ml)诱导人肝癌细胞HLA-E基因高表达,通过非经典HLA-Ⅰ(HLA-E)途径逃避NK细胞免疫监视。

Objective To investigate the expression of non-classical HLA-Ⅰ （HLA-E） induced by interferon-gama（IFN-γ）in human hepatocarcinomal cells, and its effects on natural killer cells（NK） eytotoxicity to hepatocarcinomal cells. Methods Human hepatocarcinomal cells （BEL-7402）was in vitro consistently induced, respectively by different concentrations of IFN-γ for 72 h, The expression of HLA-E in each group was detested by irnmunoeytochemistry, Western blot, semi-quantitative reverse transcriptase PCR and flow cytometry,and its effects on NK cytotoxicity to BEL-7402 cells was tested by NK killing rate, Results Compared with bland control group, HLA-E antigen, protein and mRNA were significantly increased in BEL-7402 ceils induced by different concentrations of IFN-γ （100-1000 U/mL, P〈0. 01）, the HLA-E molecules on cell surface were increased correspondingly（P 〈0. 01）. The HLA-E positive rate was higher and expression intensity stronger in high inducing concentration groups（500-1000 U/ml）than low inducing concentration groups（100-400 U/ml）. The reasonable concentration was 500 U/ml. The NK killing rate was lower in high inducing concentration groups（500-1000 U/ml）（P〈0. 01）. Conclusion The human hepatocarcinomal cells expressing HLA- E, induced by IFN-γ, might escape from NK immunosurveillance thorough pathway of non classical HLA-Ⅰ （HLA-E）.