Mei Jia-Zhuan, Niu Xin-Qing, Guo Kun-Yuan, Zhou Jian, Wei Hong-Mei
Department of Hematology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China.
Zhongguo Shi Yan Xue Ye Xue Za Zhi. 2007 Apr;15(2):288-91.
The study was aimed to investigate the expression of HLA class I molecules and MHC class I chain-related molecules A/B (MICA/MICB) in K562 and adriamycin (ADM)-resistant K562 cell lines (K562/AO2) and their effect on cytotoxicity of NK cells. Expression of HLA class I molecules and MICA/MICB on the surface of K562 and K562/AO2 cell lines were analyzed by flow cytometry. Cytotoxicity of NK cells (isolated from 3 healthy persons) against K562 and K562/AO2 cells were detected by LDH releasing assay at different effect-to-target cell ratios (E:T). In blocking experiments, anti-MHC class I monoclonal antibody (McAb) (W6/32, a pan anti-HLA class I antibody) and anti-MHC class I chain-related molecules McAb (BAMO-1, specifically against MICA and MICB) were added to the target cells at E:T of 10:1. The results showed that the expression of MHC class I chain-related molecules on K562 was higher than that on K562/AO2 (P=0.000), and HLA class I molecules were not detectable on both cells. Cytotoxicities of NK cells against K562 and K562/AO2 cells were (29.32 +/- 0.12)%, (45.33 +/- 0.78)%, (58.37 +/- 0.87)%, (72.37 +/- 0.96)% and (12.47 +/- 0.91)%, (24.36 +/- 1.11)%, (33.29 +/- 1.03)%, (53.87 +/- 1.27)% at E:T ratios of 5:1, 10:1, 20:1 and 30:1 respectively (P=0.000), the cytotoxicity of NK cells on K562 cells was significantly higher than that on K562/A02 cells at different E:T ratios. Blocking experiments confirmed that at E:T of 10:1 killing of NK cells against K562 and K562/AO2 cells was efficiently inhibited by BAMO-1, whereas W6/32 had no effect on K562 and K562/AO2 cells. It is concluded that the expression of MHC class I chain-related molecules on K562 and K562/AO2 cells is correlated with NK cell-mediated lysis. NK cells display higher cytotoxicity against parental K562 cells than multi-drug resistant K562/AO2 cells. Down-regulation of MICA/B in multi-drug resistant tumor cell lines leads to reduction of susceptibility to NK lysis.
本研究旨在探讨人白细胞抗原I类分子（HLA class I molecules）和主要组织相容性复合体I类链相关分子A/B（MICA/MICB）在K562细胞系及阿霉素（ADM）耐药的K562细胞系（K562/AO2）中的表达情况及其对自然杀伤细胞（NK细胞）细胞毒性的影响。采用流式细胞术分析K562和K562/AO2细胞系表面HLA class I分子和MICA/MICB的表达。通过乳酸脱氢酶（LDH）释放法检测不同效靶比（E:T）下，从3名健康人分离的NK细胞对K562和K562/AO2细胞的细胞毒性。在阻断实验中，将抗MHC I类单克隆抗体（McAb）（W6/32，一种泛抗HLA I类抗体）和抗MHC I类链相关分子McAb（BAMO-1，特异性针对MICA和MICB）以E:T为10:1加入靶细胞。结果显示，K562细胞上MHC I类链相关分子的表达高于K562/AO2细胞（P = 0.000），且两种细胞均未检测到HLA I类分子。在效靶比为5:1、10:1、20:1和30:1时，NK细胞对K562和K562/AO2细胞的细胞毒性分别为(29.32 ± 0.12)%、(45.33 ± 0.78)%、(58.37 ± 0.87)%、(72.37 ± 0.96)%和(12.47 ± 0.91)%、(24.36 ± 1.11)%、(33.29 ± 1.03)%、(53.87 ± 1.27)%（P = 0.000），在不同效靶比下，NK细胞对K562细胞的细胞毒性显著高于对K562/A02细胞的细胞毒性。阻断实验证实，在E:T为10:1时，BAMO-1可有效抑制NK细胞对K562和K562/AO2细胞的杀伤，而W6/32对K562和K562/AO2细胞无影响。结论是，K562和K562/AO2细胞上MHC I类链相关分子的表达与NK细胞介导的细胞溶解相关。NK细胞对亲本K562细胞的细胞毒性高于多药耐药的K562/AO2细胞。多药耐药肿瘤细胞系中MICA/B的下调导致对NK细胞溶解的敏感性降低。
