MIC基因及膜型MIC分子在急性白血病中的表达及其意义

Expression and significance of MHC class Ⅰ chain-related gene and mMIC in acute leukemia

目的探讨急性白血病（AL）患者骨髓单个核细胞（MNC）主要组织相容性复合物Ⅰ类链相关基因A／B（MICA／B）及膜型MIC分子（mMIC）的表达及其意义。方法半定量RT-PCR检测K562细胞（MICA／B阳性细胞株）、10名健康人、69例AL患者骨髓MNC中MICA／B mRNA的表达和Western blotting法检测MNC膜表面mMIC的表达，分析MIC基因及mMIC在急性髓系白血病（AML）和急性淋巴细胞白血病（ALL）中的表达差异，并以染色体核型作为判断预后的指标，间接分析mMIC表达与临床预后的关系。结果健康人骨髓MNC中未检测到MIC基因和mMIC的表达，AL患者中MICA基因阳性率49．28％，MICB基因阳性率42．03％，mMIC阳性率34．78％。AML组MICA基因阳性率60．00％，MICB基因阳性率53．33％，mMIC阳性率44．44％；而ALL组MICA基因阳性率29．17％，MICB基因阳性率20．83％，mMIC阳性率16.67％。AML组MIC基因及mMIC的表达均高于ALL组（P〈0．05）。mMIC（＋）和mMIC（-）患者预后差异有统计学意义（P〈0．05），mMIC（＋）患者预后相对好于mMIC（-）患者。结论MIC基因及mMIC在AL中表达上调和AL的发生可能有一定的关系。MIC基因及mMIC在AML表达增高，而在ALL表达低下或缺乏，可能是ALL细胞更容易免疫逃避NK和CTL细胞杀伤的一个机制。以染色体核型作为判断预后的指标，mMIC（＋）患者预后好于mMIC（-）患者，MIC可作为白血病预后相关指标之一。

Objective To detect and determine the expression and significance of MHC class Ⅰ chain-related gene A/B （MICA/B） and membrane MIC molecules （mMIC） on the bone marrow mononuclear cells （MNC） of patients with acute leukemia （AL）. Methods Expression of MICA/B gene was detected by semi-quantitative reverse transcriptase polymerase chain reaction （RT-PCR） in MIC-positive K562 cell line, bone marrow MNC from 10 healthy people and 69 cases of acute leukemia （AL）. Expression of mMIC was detected by Western blotting. The differences of the expression of MIC gene and mMIC between AML and ALL were compared. The prognosis was determined by chromosome type between patients with mMIC＋ and mMIC-. Results The expression of MIC gene and mMIC could not be detected in healthy people. The expression rate of MICA gene was 49.28 % and the MICB gene was 42.03 % and the mMIC was 34.78% in patients with AL. In AML group, the expression rate of MICA gene was 60.00 %, and the expression rate of MICB gene was 53.33 %, and the expression rate of mMIC was 44.44 %. But in ALL group, the expression rate of MICA gene was 29.17 %, of MICB gene 20.83 %, and of mMIC 16.67 %. The expression of MICA/B gene and mMIC in AML group were higher than that in ALL group （P 〈0.05）. The prognosis of patients with mMIC＋ is better than the ones with mMIC-. Conclusion The up-regulation of MIC gene and mMIC in bone marrow MNC from patients of AL may have some relationship with the occurrence of AL. The expression of MIC gene and mMIC is high in AML, and low or devoid in ALL, which would be an possible mechanism that ALL cells were easy to escape killing from NK and CTL cells. Determined by chromosome type, the prognosis of AL with mMIC positive was better than the ones with mMIC negative. MIC might be one of the factors to determine the prognosis of AL.