MICA在NK细胞杀伤胰腺癌PANC-1细胞中的作用

探讨MHC I类链相关分子A(MHC class I chain-related A,MICA)在NK细胞杀伤胰腺癌PANC-1细胞中的作用。应用NK细胞分选试剂盒从外周血中分选高纯度NK细胞用于实验,体外培养PANC-1细胞和NK细胞,应用抗体封闭法,观察NKG2D与膜型MICA识别在NK细胞杀伤PANC-1细胞中的作用。将健康志愿者NK细胞在含有sMICA阳性胰腺癌患者血清的培基液中培养,观察NK细胞对PANC-1细胞的杀伤作用。经MICA或NKG2D抗体封闭后,NK细胞的杀瘤活性较封闭前显著减弱(P0.01)。胰腺癌患者血清sMICA水平显著高于健康志愿者和慢性胰腺炎患者(P0.01),胰腺癌患者血清中的sMICA可以显著降低NK细胞对PANC-1细胞的杀伤活性。NKG2D与膜型MICA识别在NK细胞杀伤人胰腺癌PANC-1细胞中起重要作用;sMICA是造成胰腺癌免疫逃逸的重要分子机制之一。     

MICA分子在NK细胞杀伤乳腺癌中的作用

目的 观察乳腺肿瘤细胞膜MHC Ⅰ链相关分子A(MHC class Ⅰ chain-related gene A,MICA)及血清中可溶性MICA表达,探讨MICA在NK细胞杀伤乳腺癌中的作用.方法 流式细胞术检测膜型MICA(mMICA)及NK细胞表面NKG2D表达,观察膜型MICA、可溶性MICA(sMIcA)对NKG2D表达的影响;免疫组织化学检测膜型MICA及可溶性MICA的表达及分布;抗体封闭法观察膜型MICA与NKG2D相互作用.结果 乳腺细胞膜型MICA在正常组织不表达,在良性肿瘤表达量为(38.5±7.5)%,恶性肿瘤表达量为(53.2±5.6)%.可溶性MICA含量在健康成年人为阴性,在乳腺良性肿瘤患者血清中含量(76.8±22.3)pg/mL,在恶性肿瘤患者中含量(205.36±71.27)pg/mL.经NKG2D或MICA抗体封闭后,NK细胞的杀瘤活性显著减弱.含可溶性MICA的血清可明显下调NKG2D的表达.结论 大部分乳腺肿瘤细胞膜都有MICA的表达,可作为乳腺肿瘤相关性抗原.膜型MICA与NKG2D的相互识别在介导NK细胞抗乳腺癌中起重要作用,而可溶性MICA通过下调NKG2D表达介导肿瘤免疫逃逸.     

两种不同HLA-B分子对NK细胞表面受体表达的研究

目的：探讨两种HLA-B分子(HLA-B51和HLA—B39)对NK细胞表面活化性受体CDl6和抑制性受体KIR3DL1表达的调节。方法：采用流式细胞仪检测NK细胞分别与转染HLA-BSl和HLA-B39分子的K562细胞相互作用后，CD16和KIR3DL1的表达情况。结果：外周血淋巴细胞与K562细胞作用24小时后，CD56 CD16 细胞数、KIR3DL1 细胞数均明显增加。与表达HLA-B39的K562细胞相比，表达HLA-B51的K562细胞与外周血淋巴细胞作用后，CD56 CD16 细胞数、KIR3DL1 细胞数均明显下降。结论：NK细胞杀伤靶细胞时，活化性受体CD16表达上调后会伴有抑制性受体KIR3DL1的上调；HLA-B51分子表达在K562细胞后，表达外源性HLA-B51分子的K562细胞与NK细胞作用，NK细胞表面受体KIR3DL1的表达可下调，同时伴有CD16的表达下调。     

同种异体NK细胞对人脐静脉内皮细胞ECV304的杀伤活性差异及分子机制探讨

目的 探讨供者KIR分子表达差异对NK细胞杀伤人脐血内皮细胞系ECV304活性的影响,并观察参与杀伤的活化信号通路.方法 RT-PCR及流式细胞仪检测ECV304细胞NKG2D配体MICA/B、ULBP1-3表达,PCR-SSP法行HLA-A、B、Cw分型.自8例健康供者分离外周血NK细胞,流式细胞仪检测KIR2DL1的表达率,LDH释放法测定NK细胞在效靶比20∶1时对ECV304细胞的杀伤活性及anti-KIR2DL1mAb对NK细胞杀伤活性的影响.结果 ECV30细胞在mRNA水平表达MICA/B、ULBP1-3,但在膜蛋白水平均不表达.HLA分型表明,ECV304表达KIR2DL1的配体,而不表达KIR2DL2/3、KIR3DL1的配体.8例健康供者NK细胞KIR2DL1表达率有较大差异,对ECV304细胞的杀伤活性也有不同,双变量相关分析示个体KIR2DL1表达率与NK细胞对ECV304的杀伤率存在负相关(rS=-0.994,P=0.000).anti-KIR2DL1 mAb明显增强NK细胞对ECV304的杀伤活性(t=-4.860,P=0.002).结论 NK细胞对ECV304细胞的杀伤分子机制主要为HLA-KIR信号系统错配,目前已知的NKG2D配体MICMB、ULBP1-3并不参与,这有助于临床活体器官移植时在遗传指导下选择供体.     

人外周血NK细胞及NKT细胞受体及亚群的差异表达与类风湿关节炎的关系

目的:探讨初诊类风湿关节炎(RA)患者的外周血NK和NKT细胞的活化性、抑制性受体及亚群表达水平的变化,揭示其在RA发病中的可能机制。方法:检测32例初诊RA患者和15例健康人的外周血NK和NKT细胞及其活化性受体和抑制性受体,对自发和刺激后的NK、NKT细胞分泌的IFN-γ、NKT细胞和CD107a+NK细胞进行检测,分析各细胞亚群与临床指标之间的潜在关系。结果:与健康对照组相比,初诊RA患者的NK细胞的比例显著降低(P=0.026);RA患者NK细胞活化性受体NKG2D+,NKP46+和NKT细胞活化性受体NKG2C+,NKG2D+,NKP46+的比例显著增高(P=0.011,P=0.010,P<0.001,P=0.032,P=0.001);NK细胞抑制性受体KIR2DL3+、KIR3DL1+和NKG2A+和NKT细胞抑制性受体KIR2DL3+,NKG2A+的比例显著降低(P=0.002,P=0.002,P=0.014,P=0.027,P=0.002);刺激后的IFN-γ+NK和IFN-γ+NKT细胞的比例,自发和刺激后的CD107a+NK细胞的比例在RA患者中要显著高于对照组(P=0.037,P=0.004,P=0.001,P=0.001)。此外,NK细胞、抑制性NK细胞受体NKG2A+和KIR2DL3+的比例和初诊RA患者的DAS28值显著相关(r=0.357,P=0.045;r=0.399,P=0.024;r=0.468,P=0.021)。结论:人外周血NK细胞及NKT细胞受体及亚群的差异表达、细胞功能的变化可能诱发RA的自身免疫反应。     

NK细胞在肿瘤免疫治疗中的研究进展

肿瘤免疫治疗是近年来有望治愈肿瘤的最有效策略之一，为肿瘤患者带来了新的希望。自然杀伤（NK）细胞作为抗肿瘤免疫的第一道防线，在控制肿瘤的起始和转移中发挥关键作用。NK细胞的活性主要受其表面活化性受体和抑制性受体调控，其中NKG2D受体是目前研究较为深入的一个活化性受体，可识别并结合肿瘤细胞表面的NKG2D配体清除肿瘤细胞，是一个非常有潜力的肿瘤免疫治疗靶点。本综述通过总结近年来NK细胞在肿瘤免疫治疗中的最新研究进展，并重点讨论抗肿瘤免疫中NKG2D受体-配体信号轴的作用机制，以及肿瘤细胞的相关免疫逃逸分子机制，为基于NKG2D配体的肿瘤免疫治疗提供理论依据和新的思路。     

白血病患者NK细胞表面NKG2D受体及其配体MICA/B的研究

目的:研究白血病患者NK细胞表面NKG2D受体及其配体MICA/B的表达,探讨白血病细胞逃逸NK细胞杀伤的机制.方法:采用流式细胞术检测NK细胞表面NKG2D受体和骨髓有核细胞表面MICA/B配体.结果:治疗前组和完全缓解组NKG2D受体的表达均较健康组低(P＜0.05);且完全缓解组低于治疗前组(P＜0.05);治疗前组和完全缓解组MICA/B配体的表达均低于增生性贫血组(P＞0.50);完全缓解组与治疗前组比较差异无显著性(P＞0.05).结论:白血病患者体内NKG2D-MICA/B介导的NK细胞功能受抑,这可能导致白血病细胞逃逸NK细胞的细胞毒作用;白血病化疗后完全缓解时其体内NKG2D-MICA/B介导的NK细胞功能仍未恢复,且较治疗前更低.     

可溶性MICA在乳腺癌免疫逃逸中的作用

目的: 观察乳腺癌患者血清中可溶性MICA(sMICA)表达情况, 探讨sMICA在乳腺癌免疫逃逸中的作用.方法: ELISA方法检测乳腺肿瘤患者外周血sMICA的分泌.流式细胞术(FCM)检测sMICA及白细胞介素15(IL-15)对NK细胞表面NKG2D表达的影响.MTT法检测NK细胞对乳腺癌细胞的杀伤活性.结果: ELISA结果显示, 血清sMICA含量在健康成年人血清中为阴性, 在乳腺良性肿瘤患者血清中含量为(76.8±22.3)ng/L, 在恶性肿瘤患者血清中含量为(205.36±71.27)ng/L, 乳腺癌患者中血清sMICA含量高低与TNM分期呈正相关.应用含sMICA的血清与NK细胞共培养可明显下调NK细胞的杀瘤活性[(76.2±6.7)% vs (48.4±4.1)%], NK细胞表面NKG2D表达和上清中IFN-λ分泌量也下降.IL-15明显上调NK细胞表面NKG2D表达, 增加培养上清IFN-λ分泌量和增强NK对MCF-7的杀瘤活性.结论: sMICA表达与乳腺癌TNM分期正相关, sMICA通过下调NK细胞NKG2D表达水平而降低NK细胞杀瘤活性, 在肿瘤免疫逃逸中起重要作用.IL-15可以上调NK细胞NKG2D的表达并增强NK细胞杀瘤活性.     

NK细胞受体KIR2DL4的结构与功能

KIR2DL4分子是NK细胞受体(NKR)的一种,属于免疫球蛋白样(IgSF)受体家族成员,主要分布在自然杀伤(Natural killer,NK)细胞上。KIR2DL4是HLA-G分子的特异性受体,结构上具备激活性和抑制性受体的双重特点,能够通过不同途径影响NK细胞的活性,具有重要的免疫调节功能。     

树突状细胞上调MHC Ⅰ类相关抗原A表达对NK细胞活性的影响

目的:观察单核细胞、未成熟和成熟树突状细胞(DCs)表达MHC Ⅰ类相关抗原A(MICA)的情况,以及DCs表达MICA后对NK细胞活性的影响.方法:用流式细胞术分别检测单核细胞、未成熟DC(iDCs)以及LPS、TNF-α、CD40L、IL-15和IFN-α分别刺激的成熟DCs表面MICA的表达,并观察DCs表达MICA后对NK细胞表达CD69、细胞毒活性和分泌IFN-γ的影响.最后用流式细胞术检测重组NKG2D/Fc蛋白和抗IL-12单克隆抗体(mAb)对DCs激活NK细胞的影响.结果:单核细胞不表达MICA,iDCs低表达MICA.LPS、TNF-α和CD40L对DCs表达MICA无影响;但IFN-α和IL-15可促进DC上调MICA表达.DCs表达MICA后可促进NK细胞表达CD69、分泌IFN-γ、杀伤K562细胞.NKG2D/Fe蛋白可抑制NK细胞的杀伤活性和分泌IFN-γ;而抗IL-12mAb仅抑制IFN-γ分泌.结论:MICA在DCs表面的表达受局部微环境影响,且DCs表达MICA后可增强NK细胞的活性.     

膜型/可溶型MHC Ⅰ类链相关分子A及其受体NKG2D在骨肉瘤中的表达及其意义

目的探讨膜型／可溶型MHCI类链相关分子A（MICA）及其受体NKG2D在骨肉瘤中的表达及其意义。方法采用免疫组织化学（LSAB法）检测膜型MICA（mMICA）在43例骨肉瘤组织中的表达;用流式细胞仪检测上述病例中的16例患者外周血淋巴细胞NKG2D的表达;用ELISA法检测患者血清中可溶型MICA（sMICA）的水平。结果骨肉瘤细胞广泛表达mMICA（37／43）,外周血淋巴细胞NKG2D的表达普遍下降,两者的表达水平均与骨肉瘤的分化呈正相关（P〈0．05）,与临床分期呈负相关（P〈0．05）。检测16例骨肉瘤患者血清中sMICA含量,其中5例升高,且与骨肉瘤的远处转移及临床分期呈正相关（P〈0．05）。结论（1）骨肉瘤细胞表达mMICA,外周血淋巴细胞NKG2D的表达以及血清中sMICA的含量与骨肉瘤的分化及临床分期相关,因此可望作为骨肉瘤病理诊断和估计预后的生物学指标。（2）MICA-NKG2D介导的免疫监视障碍可能促进了骨肉瘤的进展。     

IL-2-activated haploidentical NK cells restore NKG2D-mediated NK-cell cytotoxicity in neuroblastoma patients by scavenging of plasma MICA

NK group 2D (NKG2D)-expressing NK cells exhibit cytolytic activity against various tumors after recognition of the cellular ligand MHC class I chain-related gene A (MICA). However, release of soluble MICA (sMICA) compromises NKG2D-dependent NK-cell cytotoxicity leading to tumor escape from immunosurveillance. Although some molecular details of the NKG2D-MICA interaction have been elucidated, its impact for donor NK (dNK) cell-based therapy of solid tumors has not been studied. Within an ongoing phase I/II trial, we used allogeneic IL-2 activated dNK cells after haploidentical stem cell transplantation for immunotherapy of patients with high-risk stage IV neuroblastoma. NKG2D levels on activated dNK cells increased strongly when compared with freshly isolated dNK cells and correlated with enhanced NK-cell cytotoxicity. Most importantly, elevated sMICA levels in patients plasma correlated significantly with impaired dNK-cell-mediated cytotoxicity. This effect could be reversed by high-dose infusion of activated dNK cells, which display high levels of surface NKG2D. Our data suggest that the provided excess of NKG2D leads to clearance of sMICA and preserves cytotoxicity of dNK cells via non-occupied NKG2D. In conclusion, our results identify this tumor immune escape mechanism as a target to improve immunotherapy of neuroblastoma and presumably other tumors.     

The natural killer cell-mediated killing of autologous dendritic cells is confined to a cell subset expressing CD94/NKG2A,but lacking inhibitory killer Ig-like receptors

The cognate NK-DC interaction in inflamed tissues results in NK cell activation and acquisition of cytotoxicity against immature DC (iDC). This may represent a mechanism of DC selection required for the control of downstream adaptive immune responses. Here we show that killing of monocyte-derived iDC is confined to the NK cell subset that expresses CD94/NKG2A, but not killer Ig-like receptors (KIR). Consistent with these data, the expression of HLA-E (i.e. the cellular ligand of CD94/NKG2A) was down-regulated in iDC. On the other hand, HLA-B and HLA-C down-regulation in iDC was not sufficient to induce cytotoxicity in NK cells expressing KIR3DL1 or KIR2DL. Remarkably, CD94/NKG2A(+)KIR(-) NK cells were heterogeneous in their ability to kill iDC and an inverse correlation existed between their CD94/NKG2A surface density and the magnitude of their cytolytic activity. It is conceivable that the reduced CD94/NKG2A surface density enables these cells to efficiently sense the decrease of HLA-E surface expression in iDC. Finally, most NK cells that lysed iDC did not kill mature DC that express higher amounts of HLA class I molecules (including HLA-E)as compared with iDC. However, a small NK cell subset was capable of killing not only iDC but also mature DC.     

Gene expression analysis of activating and inhibitory receptors of natural killer cells in patients with acute myeloblastic leukemia

PurposeNatural killer (NK) cells are cytotoxic lymphocytes, which have long been known to play an essential role in immune surveillance of tumor cells. The results of several clinical studies imply evidence of impaired activity of NK cells in acute myeloblastic leukemia (AML). The aim of this study was to investigate the gene expression of activating and inhibitory receptors of NK cells in patients with newly diagnosed AML before and after induction therapy using 7 + 3 regimen in comparison to healthy donors.Materials and methodsSixteen AML patients aged 16–64 years as well as 16 matched healthy individuals were studied. Peripheral blood samples from patients were obtained in two steps, namely, in newly diagnosed patients and 28 days after receiving induction therapy. Real-time PCR was performed to evaluate the expression levels of activating receptors, including DNAM-1 and NKp46 as well as inhibitory receptors of KIR2DL1 and NKG2A.ResultsOur results demonstrated that the newly diagnosed patients showed over 50% decrease in NKp46 expression and a 6-fold increase in KIR2DL1 expression compared to healthy controls. The mRNA expression analysis in patients after induction therapy suggested a significant decrease in mRNA expressions of KIR2DL1 and NKG2A in comparison to newly diagnosed patients.ConclusionHerewith, we show a statistical difference in mRNA expression levels of activating (NKp46) and inhibitory receptors from NK cells in newly diagnosed AML patients when compared with healthy controls or patients who received induction therapy, supporting the findings of researchers who reported the impaired NK cells cytotoxicity in AML patients.     

Sustained localized expression of ligand for the activating NKG2D receptor impairs natural cytotoxicity in vivo and reduces tumor immunosurveillance

Upregulation of the inducible gene products MICA (human) and Rae-1 (mouse) may promote tumor surveillance and autoimmunity by engaging the activating receptor NKG2D on natural killer (NK) cells and T cells. Nevertheless, sustained expression of MICA by tumors can also elicit NKG2D downregulation, perhaps indicating 'immunoevasion'. Investigating this paradox, we report here that constitutive Rae-1epsilon transgene expression in normal epithelium elicited local and systemic NKG2D downregulation, generalized but reversible defects in NK cell-mediated cytotoxicity and mild CD8(+) T cell defects. The extent of NKG2D downregulation correlated well with the incidence and progression of cutaneous carcinogenesis, emphasizing the utility of NKG2D as a marker of tumor resistance. Thus, NKG2D engagement is a natural mediator of immunosurveillance, which can be compromised by locally sustained ligand expression but potentially restored by innate immune activation.     

KIR downregulation by IL‐12/15/18 unleashes human NK cells from KIR/HLA‐I inhibition and enhances killing of tumor cells

To exploit autologous NK cells for cancer immunotherapy, it is highly relevant to circumvent killer cell immunoglobulin‐like receptor (KIR)‐mediated self‐inhibition of human NK cells by HLA‐I–expressing tumor cells. Here, we show that stimulation of NK cells with IL‐12/15/18 for two days led to downregulation of surface expression of the inhibitory KIR2DL2/L3, KIR2DL1 and KIR3DL1 receptors on peripheral blood NK cells. Downregulation of KIR expression was attributed to decreased KIR mRNA levels which could be re‐induced already 3 days after re‐culture in IL‐2. Reduced KIR2DL2/L3 expression on IL‐12/15/18–activated NK cells resulted in less inhibition upon antibody‐mediated KIR engagement and increased CD16‐dependent cytotoxicity in redirected lysis assays. Most importantly, downregulated KIR2DL2/L3 expression enabled enhanced cytotoxicity of IL‐12/15/18–stimulated NK cells against tumor cells expressing cognate HLA‐I molecules. NK cells pre‐activated with IL‐12/15/18 were previously shown to exert potent anti‐tumor activity and memory‐like long‐lived functionality, mediating remission in a subset of acute myeloid leukemia (AML) patients in a clinical trial. Our study reveals a novel mechanism of IL‐12/15/18 in improving the cytotoxicity of NK cells by reducing their sensitivity to inhibition by self–HLA‐I due to decreased KIR expression, highlighting the potency of IL‐12/15/18–activated NK cells for anti‐tumor immunotherapy protocols.     

IL-2促进PBMC来源的NK、NKT、CD8+T细胞高表达NKG2D

目的 观察大剂量IL-2活化的人外周血单个核细胞（PBMC）中，NKG2D在NK细胞、T细胞和NKT细胞表面的表达规律。方法 使用三重免疫荧光标记的流式细胞术检测NKG2D的表达情况。使用sMICA蛋白与人PBMC共同培养，之后使用流式细胞术分析NKG2D在NK细胞中的表达情况。使用半定量RT-PCR方法检测大剂量IL-2活化的人PBMC中NKG2D及其锚定蛋白DAP10 mRNA的表达变化。结果 使用大剂量IL-2活化人PBMC细胞后，NKG2D在NK细胞、CD^＋T细胞和NKT细胞表面的表达均增加，但是在CD4^＋T细胞表面始终不表达。同时IL-2可以拮抗sMICA对NKG2D的下调作用。半定量RT-PCR结果显示，使用大剂量IL-2活化人PBMC之后，NKG2D及其锚定蛋白DAP10的mRNA水平并不发生明显变化。结论 大剂量IL-2培养人PBMC之后，NKG2D在NK细胞、CD8^＋T细胞和NKT细胞表面的表达均增加，可能是PBMC活化并获得广谱抗肿瘤效应的机制之一．     

c‐Cbl regulates MICA‐ but not ULBP2‐induced NKG2D down‐modulation in human NK cells

The NKG2D activating receptor on human NK cells mediates “altered self” recognition, as its ligands (NKG2DLs) are upregulated on target cells in a variety of stress conditions. Evidence collected in the past years shows that, even though expression of NKG2DLs acts as a danger signal that renders tumor cells susceptible to cytotoxicity, chronic exposure to soluble or membrane‐bound NKG2DLs can lead to down‐modulation of receptor expression and impairment of NKG2D‐mediated cell functions. Here, we evaluated whether different cell‐bound NKG2DLs, namely MICA and ULBP2, are equivalently able to induce NKG2D down‐modulation on human NK cells. We found that although both ligands reduce NKG2D surface expression, MICA promotes a stronger receptor down‐modulation than ULBP2, leading to a severe impairment of NKG2D‐dependent NK‐cell cytotoxicity. We also provide evidence that the ubiquitin pathway and c‐Cbl direct MICA‐induced but not ULBP2‐induced NKG2D internalization and degradation, thus identifying a molecular mechanism to explain the differential effects of MICA and ULBP2 on NKG2D expression. A better understanding of the molecular mechanisms employed by the different NKG2DLs to control NKG2D surface expression could be useful for the development of anti‐tumor strategies to restore a normal level of NKG2D receptors on human NK cells.     

重组可溶性MHC Ⅰ类相关蛋白A对NK细胞生物学活性的影响

目的:研究体外重组可溶性MHC Ⅰ类相关蛋白A(sMICA)对NK细胞杀伤靶细胞活性、分泌IFN-γ、增殖和凋亡的影响.方法:将重组sMICA蛋白与人外周血NK细胞相互作用过夜后,流式细胞仪检测NK细胞杀伤K562靶细胞的能力;ELISA检测培养上清IFN-γ浓度;MTS/PMS法检测sMICA对NK细胞增殖的影响;给NK细胞标记Annexin V和碘化丙啶检测凋亡情况.结果:可溶性MICA抑制NK细胞杀伤K562细胞的活性,下调IFN-γ的分泌,却对NK细胞的增殖和凋亡没有影响.结论:肿瘤细胞表面脱落的sMICA抗原可通过抑制NK细胞活性而逃逸机体的免疫监视功能.