干扰素α对恶性造血细胞系主要组织相容性复合体I类链相关蛋白A表达的上调作用

Up-regulation of major histocompatibility complex class I chain-related protein A expression in the malignant hematopoietie cell lines by interferon-a

目的观察干扰素a（IFN-a）对恶性造血细胞系主要组织相容性复合体（MHC）I类链相关蛋白A（MICA）表达的影响。方法反转录-聚合酶链反应（RT-PCR）法检测人类慢性髓系白血病细胞K562及人类伯基特淋巴瘤细胞Raji细胞MICAmRNA的表达，免疫组织化学法检测MICA蛋白的表达，四甲基偶氮唑蓝（MTF）比色法检测人类外周血自然杀伤（NK）细胞对肿瘤细胞的杀伤。结果K562细胞MICA表达阳性，Raji细胞MICA表达阴性。Raji和K562细胞分别在1000U／ml IFN-a诱导24h和48h时MICAmRNA开始表达上调（t=17．016，P〈0．05；t=5．616，P〈0．05）。72hRaji细胞和K562细胞分别在500U／ml和1000U／ml诱导条件下MICAmRNA表达开始上调（t=6．622，P〈0．05；t=9．071，P〈0．05）。IFN—Ot对MICAmRNA表达的上调作用呈一定时间和剂量依赖关系，且蛋白与mRNA表达水平一致。1000U／ml IFN—a诱导72h后，Raji细胞和K562细胞对NK细胞杀伤的敏感性明显上调（t=20．016，P〈0．05；t=7．969，P〈0．05），抗MICA抗体封闭MICA后，NK细胞对Raji细胞杀伤率恢复至诱导前水平（t=0．393，P〉0．05），而K562细胞则低于诱导前水平（t=9．841，P〈0．05）。结论IFN—a上调了恶性造血细胞中MICA基因的转录表达，继而增强了NK细胞对其识别与杀伤。

Objeαive To investigate the effeα of interferon-α （IFN-α） on expression of major histocompatibility complex （MHC） class I chain-related protein A （MICA） in the malignant hematopoietic cell lines. Methods The myeloid leukemia cell lines K562 and B-cell lymphoma cell line Raji were treated with IFN-α. The expression of MICA was measured by RT-PCR and immunohistochemical staining at mRNA and protein level. The cytotoxicity of human NK cells to the IFN-α treated malignant hematopoietic cells was deteαed by MTr method. Results After being treated with 1000 U/ml IFN-α, up-regulation of MICA mRNA in Raji and K562 cells were respeαively found in 24 h and 48 hours （t =17.016, P 〈0.05; t =5.616, P 〈0.05）. After being treated with IFN-ot 72 hours, up-regulation of MICA mRNA in K562 and Raji were found at the dose of 500 U/ml and 1000 U/ml dose （t =6.622, P 〈0.05; t =9.071, P 〈0.05）. The mRNA and protein expression of MICA were up-regulated by IFN-ot in the two malignant hematopoietic cells in a time and dose- dependent manner. After being treated with 1000 U/ml IFN-α for 72 hours, the susceptibility of the two malignant hematopoietic cells to NK cytolysis was significantly increased （t = 20.016, P 〈0.05; t = 7.969, P 〈0.05）. Moreover, the up-regulated susceptibility can be blocked by anti-MICA antibody. Conclusion IFN-ot can up-regulate the MICA expression in the malignant hematopoietic cell lines and thereby enhance the susceptibility to cytolysis of NK cells.