原发性胆汁性肝硬化HLA-A*0201限制性PDC-E2特异性CTL功能分析

目的：探讨原发性胆汁性肝硬化（PBC）中HLA-A＊ 0201限制的PDC-E2159-167特异性CTL与PDC-E2165-174特异性CTL功能。方法：分析15例HLA-A＊0201阳性（A2＋）PBC患者抗原肽PDC-E2159-167、PDC-E2165-174诱导的CTL对以表达HLA-A＊ 0201分子的T2细胞作为靶细胞的细胞毒性作用，并利用四聚体技术结合细胞内因子染色研究PDC-E2159-167特异性CTL与PDC-E2165-174特异性CTL分泌细胞因子（IFN-γ、IL-4和TNF-α）情况。结果：15例A2＋PBC患者中，12例PDC-E2159-167诱导的CTL和10例PDC-E2165-174诱导的CTL对负载相应抗原肽的靶细胞特异杀伤活性大于10%（E∶T=40∶1），而对照组则均小于10%；15例A2＋PBC患者从PBMC诱导的PDC-E2159-167特异性CTL和PDC-E2165-174特异性CTL中分泌IFN-γ细胞比值分别为0.33%±0.24%（0%～0.86%）、0.27%±0.24%（0%～0.75%），未检测到分泌TNF-α或IL-4的PDC-E2159-167或PDC-E2165-174特异性CTL。结论：结果表明，大部分PBC患者中HLA-A＊ 0201限制性PDC-E2159-167特异性CTL和PDC-E2165-174特异性CTL具有特异杀伤活性，HLA-A＊ 0201限制性PDC-E2特异性CTL主要分泌IFN-γ并非IL-4、TNF-α。     

原发性胆汁性肝硬化PDC-E2特异性T细胞拮抗性模拟肽的筛选

目的筛选可拮抗原发性胆汁性肝硬化（PBC）中PDC-E2165-174特异性CTL功能的模拟肽.方法以自身抗原表位PDC-E2165-174（LLAEIETDKA）为原型肽,采用丙氨酸突变扫描法,通过亲和力分析及其对PDC-E2165-174特异性CTL细胞毒性和分泌细胞因子等功能的抑制效应,从中筛选拮抗性模拟肽.结果8条模拟肽中,5号位突变的模拟肽（I5A）显示与HLA-A＊0201分子高亲和力,5名PBC患者PDC-E2特异性CTL对其负载的T2细胞的杀伤率均小于10%,并且I5A也未能诱导PBC患者PDC-E2特异性CTL产生IFN-γ.在原型肽的存在下,I5A可抑制PDC-E2165-174 CTL细胞毒性和分泌IFN-γ,随着模拟肽浓度增加,抑制效应越强,在10 μmol/L浓度时可以明显抑制PDC-E2165-174 CTL的细胞毒活性和分泌IFN-γ的能力.结论模拟肽I5A（LIAEAETDKA）可能是PDC-E2165-174特异性CTL的一个拮抗性多肽,其抑制效应并不是其能竞争结合靶细胞上的HLA-A＊6201分子,而是对TCR的一种拮抗作用,为将来设计以TCR为基础的特异性免疫治疗提供实验依据.     

人工抗原提呈细胞的制备和应用的研究

目的 制备人工抗原提呈细胞（artificial antigen presenting cell,aAPC）并用它从HLA-A2阳性健康个体外周血单个核细胞（PBMC）中诱导和扩增特异性细胞毒性T淋巴细胞（CTL）.方法 将HLA-A2-EBV四聚体分子和抗CD28抗体分子吸附固定在细胞大小的聚苯乙烯乳胶微球（5μm）表面制成aAPC;采用流式细胞仪表型分析;aAPC和HLA-A2阳性个体人外周血单核细胞进行混合淋巴细胞反应;用HLA-A＊0201-EBV四聚体染色法检测特异性CTL的频率;应用细胞内细胞因子染色法检测特异性CTL功能性细胞因子IFN-γ的分泌;采用LDH释放法检测特异性CTL的特异杀伤活性.结果 流式细胞仪分析显示微球表面吸附有HLA-A2-EBV四聚体分子和抗CD28抗体分子;四聚体检测及细胞内细胞因子染色法检测与经典细胞毒试验结果一致,结果表明aAPC在体外可诱导抗原特异性CTL的生成.结论 aAPC制备成功,并在体外有效地诱导抗原特异性CTL的生成.     

HLA-A*0201/CAP-1四聚体在结直肠癌研究中的应用1

目的:应用HLA-A*0201/CAP-1四聚体,分析HLA-A*0201+CEA+结直肠癌患者的外周血及癌旁肠系膜引流淋巴结的特异性CTLs的数量。方法:分离健康人(18例)PBMC和结直肠癌(23例)患者PBMC以及癌旁肠系膜引流淋巴结的淋巴细胞,应用流式细胞术,以HLA-A*0201/CAP-1和HLA-A*0201/FLUmp四聚体检测CAP-1和FLUmp特异性CTLs的频率。结果:在25例HLA-A*0201+个体中,结直肠癌组和正常组外周血单个核细胞中HLA-A*0201/FLU四聚体+CD8+细胞的频率分别为(0.671±0.421)%和(0.564±0.408)%,两组之间无显著差异(P=0.525)。结直肠癌组和正常组外周血单个核细胞中HLA-A*0201/CAP-1四聚体+CD8+细胞的频率分别为(2.409±2.385)%和(0.020±0.021)%,两组之间有显著差异(P=0.008)。结论:HLA-A*0201+结直肠癌患者HLA-A*0201/CAP-1四聚体+CD8+细胞的频率升高,说明CEA特异性CTLs在结直肠癌患者的免疫监视功能中具有重要的作用。对存在针对肿瘤抗原的特异性CTLs却无法阻止肿瘤进展的具体机制需要更加深入的研究。     

人乳头状瘤病毒11型E7抗原HLA-A*0201限制性细胞毒性T淋巴细胞表位的功能鉴定

目的 筛选和鉴定人乳头状瘤病毒11型E7抗原(HPVllE7)HLA-A*0201限制性细胞毒性T淋巴细胞(cytotoxic T lymphocyte,CTL)表位.方法 预测HPVllE7抗原HLA-A*0201限制性CTL表位并合成相对应的表位多肽和四聚体(tetramer),即HPVllE7 7-15(TLKDIVLDL)、15-23(LQPPDPVGL)、47-55(PLTQHYQIL)、81-89(DLLLGTLNI)和82-90(LLLGTLNIV).从健康HLA-A*0201成人外周血单一核细胞诱导树突状细胞(DC)并负载上述表位多肽,流式细胞技术检测DC成熟分化标记及ELISA法检测DC分泌的IL-12;成熟DC负载各组多肽后观察DC激活T淋巴细胞的效应,ELISA法检测T细胞分泌的IFN-γ;四聚体检测抗原特异性CD8+ T细胞及乳酸脱氢酶(LDH)释放法评价DC诱导的CTL对靶细胞的特异性体外杀伤效应.结果 预测的5条HPVllE7表位多肽均能诱导DC的成熟分化;E7 7-15、82-90和15-23多肽负载的DC能激活T淋巴细胞分泌高水平IFN-γ;E7 7-15多肽负载的DC能刺激特异性tetramer+CD8+细胞增殖且其诱导的CTL对HPVllE7/293细胞产生高效率的特异性杀伤作用(P<0.05).结论 筛选并鉴定出1条HPVllE7HLA-A*0201限制性CTL表位E7 7-15(TLKDIVLDL),负载该表位肽的DC体外可诱导高效、特异性的CTL效应,抗原性较强,有可能作为HPV感染治疗用肽疫苗的候选表位.     

HLA-A2+供者外周血hCMV特异性CTL的定量及其表型分析

目的:利用加载人巨细胞病毒(hCMV)结构蛋白pp65衍生抗原肽NLV(pp65495-503)的HLA-A0201(A2-NLV)四聚体,探讨四聚体染色条件的优化及其在特异性CTL表型分析中的应用。方法:取HLA-A2 供者外周血,以A2-NLV四聚体/PE在不同条件下染色,然后以anti-CD3-FITC和anti-CD8-APC标记,流式细胞术分析染色结果,寻找四聚体最佳染色条件,并分析特异性CTL的表型和活化抗原表达。结果:以全血样进行四聚体染色结果优于分离的PBMC。A2-NLV四聚体用量为0.3μg时,与100μL全血于4℃温育1h,特异性染色效果最佳,而与CD8-T细胞非特异性结合很低。以此优化条件进行特异性CTL表型分析,结果显示CD28阳性的A2-NLV四聚体特异性CTL的百分率较非特异性CTL低,表达CD57的百分率较非特异性CTL高,CD25分子只表达于活化的特异性CTL上。结论:通过对染色条件进行优化可明显提高四聚体染色的特异性,降低非特异性结合,优化的四聚体染色法能用于抗原特异性CTL的表型和功能分析。     

三种常见HBV抗原肽-HLA-A*0201复合物四聚体的构建及初步检测应用

目的 体外构建三种常见HBV抗原肽-HLA-A*0201复合物四聚体,并初步用该三种四聚体对抗原肽特异性的细胞毒性T细胞(CTL)进行了初步检测.方法 原核高效表达的HLA-A*0201-BSP和β2m蛋白,分别和三种HBV抗原肽(HBVCore18-27,Env335-343,Po1575-583)体外复性折叠成可溶性的HLA-A*0201抗原肽复合物单体,经BirA酶作用并通过凝胶过滤层析法纯化复合物单体,分别将复合物单体与藻红蛋白标记的链霉亲和素按一定比例耦合构建成相应的三种抗原肽四聚体.最后进行流式细胞仪检测.结果 Dot-ELISA和ELISA检测显示获得了三种具有天然构象的生物素化的HBV抗原肽-HLA-A*0201复合物单体.构建的三种四聚体均可以检测到相应特异性的CTL,在自限性感染患者体内针对乙肝核心抗原(core18-27)的CTL细胞频数(0.18%)高于针对聚合酶抗原(po1575-583)(0.08%)和包膜抗原(env335-343)(0.06%).结论 成功构建了三种具有完整构象的生物素化HBV抗原肽-HLA-A*0201复合物单体,所构建的三种四聚体都可以检测到抗原特异性的CTL.     

健康青年人HCMV特异性CD8+T细胞频率和表型分析

目的 利用负载pp65495.503抗原肽的HLA-A*0201四聚体染色结合流式细胞术,分析HLA-A2 健康青年供者外周血中HCMV pp65495-503特异性记忆CD8 T细胞的频率和表型.方法 以优化的四聚体染色方法对22例中国青年供者全血进行染色,用流式细胞仪对样品进行三色荧光分析.结果 健康中国青年人外周血中存在高频率的pp65495-503特异性CD8 T细胞,占CD8 T细胞的百分率为0.14～6.84%(均数2.45%);表型分析显示其CD28 细胞占四聚体阳性和四聚体阴性细胞的百分率分别为为32.5%(±21.7%)和58.58%(±10.4%)(P＜0.001);CD57 细胞占四聚体阳性和四聚体阴性细胞的百分率分别为55.8%(±18.4%)和27.4%(±8.3%)(P＜0.001).同时,对三例健康青年人CD8 T细胞上多种表面分子的详细分析显示,pp65495-503特异性记忆CD8 T细胞有不同比率的细胞表达CD62L、CD45RO、CD38和CD27,而且还有一定比例的细胞表达CD45RA,但不表达活化抗原CD69分子.结论 青年中国人外周血中存在高频率的HCMV特异性CD8 T细胞,这些细胞的表型存在高度异质性,可能是处于不同分化阶段的记忆和效应细胞群体组成.     

sHLA-A*0201-抗原肽四聚体的构建与功能检测

目的：构建有功能的sHLA-A＊0201-抗原肽四聚体，建立一套HLA Ⅰ类分子／抗原肽的四聚体制备技术。方法：利用基因工程及体外折叠技术构建sHLA-A＊0201-LMP2A426-434复合物分子，并在BirA酶的作用下生物素化。与荧光标记的亲和素衍生物以分子数4：1结合而形成HLA-A＊0201-LMP2A426-434四聚体。获得的四聚体对长期混合淋巴细胞培养中增殖的抗原特异性CTL进行检测，同时用细胞毒实验验证。结果：荧光标记的亲和素与生物素化的HLA-A＊0201-抗原肽复合物分子正确结合，制备的四聚体能够与长期混合淋巴细胞培养出的特异性T细胞结合。结论：从结构与功能上证实成功地获得有功能的HLA-A＊0201-抗原肽复合物四聚体。为进一步研究T细胞识别机制与功能奠定了基础，也为过程复杂的HLA-抗原肽四聚体制备提供了可行的免疫学监控方法。     

p210~(bcr-abl)抗原的T细胞表位鉴定及其特异性CTL细胞检测

目的:探讨p210~(bcr-abl)抗原的免疫原性,预测并鉴定该蛋白来源的HLA-A2限制性T细胞表位,并在慢性粒细胞白血病患者中检测其特异性CTL细胞分布.方法:首先利用生物信息学软件预测并选取2个p210~(bcr-abl)来源的表位:~(BCR-ABL)_(642)与~(BCR-ABL)_(926m);T2细胞亲和力实验鉴定短肽与HLA-A2分子的亲和力;然后制备分别锚合这2种表位的可溶性HLA-A2四聚体,流式检测术检测其特异性CTL细胞在CML患者外周血CD8+T细胞中的频率.结果:与健康人群相比,~(BCR-ABL)_(642)和~(BCR-ABL)_(926m)肽表位限制性CTL细胞的频率在CML患者均明显升高(P<0.01);而来自流感病毒短肽的特异性CTL细胞在两个群体中无统计学差异(P>0.05);另外,~(BCR-ABL)_(642)特异性CTL细胞的频率在CML慢性期和急变期之间有统计学差异(P<0.05).结论:所选2种肽表位均具有免疫原性,可建立基于这2种短肽的免疫治疗措施.     

CD4 T-cell autoreactivity to the mitochondrial autoantigen PDC-E2 in AMA-negative primary biliary cirrhosis

Approximately 5% of patients with primary biliary cirrhosis (PBC) lack characteristic anti-mitochondrial antibodies (AMA). Yet clinically AMA(+) and AMA(-) patients are similar. Using both AMA(+) and AMA(-) patients, we quantitated the frequency of autoreactive T cells that respond to the major CD4 T-cell epitope, PDC-E2 163-176, using limiting dilution assays and quantitation of IFN-gamma, IL-10 and IL-4. Further, based on data that both PBC patients and healthy subjects have CD4(+) T cells that recognize PDC-E2 163-176 but with differing costimulation requirements, assays were performed using two different antigen-presenting cell (APC) systems: either autologous peripheral blood mononuclear cells (PBMC) or HLA DR53 transfected mouse fibroblast cell lines (L-DR53). When costimulation-incompetent L-DR53 were used as APCs, the PDC-E2 CD4 T-cell frequency and capacity for IFN-gamma production were equivalent in both AMA(+) and AMA(-) patients but the frequencies of such cells were significantly lower in normals, with IL-10 production similar in all three groups. Thus, in PBC there is 'universal' autoreactive CD4(+) T-cell immune responsiveness to the critical autoantigen, PDC-E2. These observations emphasize that the mitochondrial autoreactivity in PBC is a multi-lineage response and hence, AMA-negative PBC may be an anachronism that refers only to sera autoantibodies.     

Dissecting cytotoxic T cell responses towards the NY-ESO-1 protein by peptide/MHC-specific antibody fragments

NY-ESO-1 is a germ cell antigen aberrantly expressed by different tumor types that elicits strong humoral and cellular immune responses, representing one of the most promising candidates for vaccination of cancer patients. A detailed analysis of CD8(+) T cells generated in vaccine trials using NY-ESO-1-derived peptides (157-165 and 157-167) revealed that the dominant immune response was directed against a cryptic epitope (159-167) diverting the immune response from tumor recognition. Only CTL reactivity to the NY-ESO-1(157-165) peptide appeared to be capable of lysing NY-ESO-1/HLA-A0201-expressing tumor cells. To study the process of NY-ESO-1 peptide presentation by tumor cells in more detail we generated a high-affinity (K(D)=60 nM) antibody fragment that specifically recognizes the NY-ESO-1(157-165) peptide/HLA-A0201 complex. Peptide variants such as the NY-ESO-1(157-167) peptide or the cryptic NY-ESO-1(159-167) peptide were not recognized. The antibody fragment blocked in a dose-dependent fashion the recognition of NY-ESO-1/HLA-A2-positive tumor cells by NY-ESO-1(157-165) peptide-specific CD8(+) T cells. This antibody fragment is a novel reagent that binds with TCR-like specificity to the NY-ESO-1(157-165)/HLA-A2 complex thus distinguishing between CTL responses against immunological meaningful or cryptic NY-ESO-1-derived peptides. It may therefore become a useful monitoring tool for the development of NY-ESO-1-based cancer vaccines.     

Identification of a new HLA-A*0201-restricted CD8+ T cell epitope from hepatocellular carcinoma-associated antigen HCA587

For the development of peptide-based cancer immunotherapies, we aimed to identify specific HLA-A*0201-restricted CTL epitopes in hepatocellular carcinoma (HCC) associated antigen HCA587, which has been identified as a member of the cancer/testis (CT) antigens highly expressed in HCC. We first combined the use of an HLA-A*0201/peptide binding algorithm and T2 binding assays with the induction of specific CD8(+) T cell lines from normal donors by in vitro priming with high-affinity peptides, then IFN-gamma release and cytotoxicity assays were employed to identify the specific HLA-A*0201 CD8(+) T cell epitope using peptide-loaded T2 cells or the HCA587 protein(+) HCC cell line HepG2. In the six candidate synthesized peptides, two peptides showed higher binding ability in T2 binding assays. No. 2 peptide, encompassing amino acid residues FLAKLNNTV (HCA587(317-325)), was able to activate a HCA587-specific CD8(+) T-cell response in human lymphocyte cultures from two normal donors and two HCC patients, and these HCA587-specific CD8(+) T cells recognized peptide-pulsed T2 cells as well as the HCA587 protein(+) HCC cell line HepG2 in IFN-gamma release and cytotoxicity assays. The results indicate that no. 2 peptide is a new HLA-A*0201-restricted CTL epitope capable of inducing HCA587-specific CTLs. Our data suggest that identification of this new HCA587/HLA-A*0201 peptide FLAKLNNTV may facilitate the design of peptide-based immunotherapies for the treatment of HCA587-bearing HCC patients.     

The use of HLA-A*0201-transfected K562 as standard antigen-presenting cells for CD8(+) T lymphocytes in IFN-gamma ELISPOT assays.

ELISPOT assays are increasingly used for a direct detection and quantification of single antigen-specific T cells in freshly isolated peripheral blood mononuclear cells (PBMC). They are particularly attractive for the monitoring of specific T lymphocyte responses in clinical trials assessing antigen-specific immunizations in patients with cancer or chronic viral infections. However, one major limitation for the broad clinical implementation of ELISPOT assays is the lack of an inexhaustible source of suitable HLA-matched antigen-presenting cells (APC). Currently available allogeneic or xenogeneic APC (such as the human lymphoid hybrid T2 or HLA-transfected insect cells) can either lead to strong background spot production by APC-reactive T lymphocytes or have a low antigen presentation capability. Both phenomena can prevent the detection of low frequency T cell responses in PBMC. In search of alternative APC for ELISPOT assays, the human chronic myelogenous leukemia cell line K562 that per se does not express HLA class I and class II molecules on the cell surface was transfected with the HLA-A*0201 gene. Clonal HLA-A*0201-expressing K562 (K562/A*0201) cells were able to process and present endogenously expressed and exogenously loaded melanoma peptide antigens to HLA-A*0201-restricted cytolytic T lymphocyte clones in cytotoxicity and IFN-gamma ELISPOT assays. K562/A*0201 cells were then used as APC in IFN-gamma spot assays to detect ex vivo CD8(+) T lymphocytes responsive to known HLA-A*0201-binding peptide epitopes derived from cytomegalovirus, Epstein-Barr virus, influenza virus and melanoma in PBMC from HLA-A*0201-positive donors. In the majority of cases, peptide-pulsed K562/A*0201 cells were similarly efficient in the ability to visualize single antigen-specific CD8(+) T lymphocytes when compared to T2 cells. However, in contrast to T2, background reactivity of CD8(+) T cells responsive to unpulsed K562/A*0201 was regularly found to be negligible, thereby enhancing the sensitivity of the ELISPOT assay, particularly in donors with strong anti-T2 reactivity. K562 cells transfected with HLA-A*0201 or other HLA genes can serve as standard APC for monitoring T lymphocyte responses against tumor and viral peptide antigens.     

Generation and characterization of malaria-specific human CD8(+) lymphocyte clones: effect of natural polymorphism on T cell recognition and endogenous cognate antigen presentationby liver cells

CD8(+) cytolytic T lymphocytes (CTL) play a fundamental role in the clearance of malaria parasites from the liver in mouse models. In humans, however, only low levels of parasite-specific CD8(+) T lymphocytes have been observed in individuals living in endemic areas. In the present study, we identified high levels of circulating CD8(+) T lymphocytes specific for a previously described HLA-A2-restricted CTL epitope of the circumsporozoite (CS) protein of Plasmodium falciparum in an adult living in Burkina Faso, as evidenced by IFN-gamma ELISPOT assay and MHC-tetramer technology. After cloning by limiting dilution culture, T cell recognition of natural CS variants of P. falciparum was studied. The results demonstrate that naturally occurring variations drastically affect residues critical for T cell recognition as only two out of nine sequences analyzed were efficiently recognized by the CTL clones. These clones were also used to analyze T cell recognition of the endogenously presented cognate antigen. We observed efficient antigen recognition of both HLA-A*0201-transfected murine antigen presenting cells and liver cells from HLA-A*0201/K(b)-transgenic mice upon infection with recombinant vaccinia virus encoding the CS protein (WR-CS). More importantly, we demonstrate for the first time efficient recognition of WR-CS-infected human liver cells.     

Lack of tumor recognition by hTERT peptide 540-548-specific CD8(+) T cells from melanoma patients reveals inefficient antigen processing

Telomerase is a ribonucleoprotein complex responsible for the maintenance of the length of the telomeres during cell division, which is active in germ-line cells as well as in the vast majority of tumors but not in most normal tissues. The wide expression of the human telomerase catalytic subunit (hTERT) in tumors makes it an interesting candidate vaccine for cancer. hTERT-derived peptide 540-548 (hTERT(540)) has been recently shown to be recognized in an HLA-A*0201-restricted fashion by T cell lines derived from peptide-stimulated peripheral blood mononuclear cells (PBMC) from healthy donors. As a first step to the inclusion of this peptide in immunotherapy clinical trials, it is crucial to assess hTERT(540)-specific T cell reactivity in cancer patients as well as the ability of hTERT-specific CD8(+) T lymphocytes to recognize and lyse hTERT-expressing target cells. Here, we have analyzed the CD8(+) T cell response to peptide hTERT(540) in HLA-A*0201 melanoma patients by using fluorescent HLA-A*0201/hTERT(540) peptide tetramers. HLA-A*0201/hTERT(540) tetramer(+) CD8(+) T cells were readily detected in peptide-stimulated PBMC from a significant proportion of patients and could be isolated by tetramer-guided cell sorting. hTERT(540)-specific CD8(+) T cells were able to specifically recognize HLA-A*0201 cells either pulsed with peptide or transiently transfected with a minigene encoding the minimal epitope. In contrast, they failed to recognize hTERT-expressing HLA-A*0201(+) target cells. Furthermore, in vitro proteasome digestion studies revealed inadequate hTERT processing. Altogether, these results raise questions on the use of hTERT(540) peptide for cancer immunotherapy.     

Enhanced immunogenicity of CTL antigens through mutation of the CD8 binding MHC class I invariant region

CD8(+) cytotoxic T lymphocytes (CTL) are key determinants of immunity to intracellular pathogens and neoplastic cells. Recognition of specific antigens in the form of peptide-MHC class I complexes (pMHCI) presented on the target cell surface is mediated by T cell receptor (TCR) engagement. The CD8 coreceptor binds to invariant domains of pMHCI and facilitates antigen recognition. Here, we investigate the biological effects of a Q115E substitution in the alpha2 domain of human leukocyte antigen (HLA)-A*0201 that enhances CD8 binding by approximately 50% without altering TCR/pMHCI interactions. Soluble and cell surface-expressed forms of Q115E HLA-A*0201 exhibit enhanced recognition by CTL without loss of specificity. These CD8-enhanced antigens induce greater CD3 zeta chain phosphorylation in cognate CTL leading to substantial increases in cytokine production, proliferation and priming of naive T cells. This effect provides a fundamental new mechanism with which to enhance cellular immunity to specific T cell antigens.     

新型的抗线粒体抗体M2亚型抗体的检测方法在原发性胆汁性肝硬化诊断中的可靠性分析

目的研究以天然M2抗原和BPO融合蛋白M2-3E（BPO）为靶抗原的ELISA法（抗-M2-3EELISA）检测抗线粒体抗体M2亚型（AMA-M2）抗体在原发性胆汁化肝硬化（PBC）诊断中的可靠性。方法分别用间接免疫荧光法（IFL）、以丙酮酸脱氢酶复合体（PDC）为靶抗原的ELISA法（抗-PDCELISA）、以三联体（BPO）为靶抗原的ELISA法（抗-3EELISA）、以天然M2抗原和BPO融合蛋白M2-3E（BPO）为靶抗原的ELISA法（抗-M2-3EELISA）检测107例PBC、167例疾病对照和30例正常对照血清中的AMA-M2抗体。结果107例PBC患者用抗-M2-3EELISA、抗-3EELISA、抗-PDCELISA和IFL4种方法检测AMA-M2的检出率（敏感性）分别为99/107（92.5%）、94/107（87.9%）、78/107（72.9%）、87/107（81.3%）,特异性分别为97.3%、98.5%、98.5%、97.3%。抗-M2-3EELISA法AMA-M2的检出率（92.5%）显著高于抗-PDCELISA法（72.9%）（P〈0.001）、IFL法（81.3%,P〈0.001）,高于抗-3EELISA（87．9％）。在20例IFL检测AMA—M2为阴性的PBC患者中,用抗-M2—3EELISA法AMA—M2的检出率为11／20（55％）。抗-M2-3EELISA和IFL的重叠度为85．0％（91／107）。结论抗-M2-3EELISA法具有比IFL、抗-PDCELISA法和抗-3EELISA更高的敏感性,特异性达97-3％。因此,抗-M2-3EELISA法可作为第一轮AMA-M2的筛查,但不可以单独用于诊断PBC的标记。     

Identification of novel HLA-A*0201-restricted epitopes from anterior gradient-2 as a tumor-associated antigen against colorectal cancer

Anterior gradient-2 (AGR2) promotes tumor growth, cell migration and cellular transformation and its enhanced expression is almost completely restricted to malignant tissues, thus making AGR2 an interesting target for the development of immunotherapeutic strategies. We investigated whether the AGR2 molecule comprises human leukocyte antigen (HLA)-A*0201-binding epitopes recognized by human cytotoxic T lymphocytes (CTLs), which could be targeted in dendritic cell (DC)-based cancer immunotherapy against colorectal cancer (CRC). We reviewed the sequence of AGR2 for peptides that could potentially bind to HLA-A*0201 with the aid of a computer-based program. Five candidate peptides with different binding scores were synthesized and tested. These peptides were then assessed for their immunogenicity to elicit specific immune responses mediated by CTLs in vitro by means of enzyme-linked immunospot assays and CTL assays. AGR2 was highly expressed in several CRC cell lines, including DK01, DLD1, KM12C, HCT-8 and HT-29. DCs pulsed with AGR2-P2 (aa 11-19; LLVALSYTL) or AGR2-P4 (aa 127-135; RIMFVDPSL) generated potent CTLs that could lyse T2 cells pulsed with AGR2-P2 or AGR2-P4 and HLA-A0201(+) AGR2-positive CRC cell lines in a strong dose-dependent and HLA-A*0201-restricted manner. In conclusion, these novel epitopes derived from AGR2 protein may be attractive candidates for DC-based immunotherapy for CRC.     

Proteasome is required for class I-restricted presentation by Fcgamma receptor-mediated endocytosis in primary biliary cirrhosis

There is a considerable database on the effector mechanisms for CD8 recognition of PDC-E2 in primary biliary cirrhosis (PBC). In particular, the specific roles of MHC class I, the mitochondrial autoepitope, and the liver-specific T cell precursor frequency, are defined for HLA-A2.1 patients. There is evidence for a role of MHC class I-mediated presentation of exogenous antigens, or cross-presentation, in the development of the antimitochondrial response and a contributory role of Fcgamma receptor-mediated uptake of autoantigen-autoantibody complexes for the induction of a PDC-E2 specific autoreactive CTL response. Based on this background, we examined potential intracellular pathways for processing the immunodominant mitochondrial autoantigen, PDC-E2, by dendritic cells (DC). In particular, we studied the effects of the proteasome inhibitor lactacystin and the endosomal acidification inhibitor bafilomycin on the induction of PDC-E2-specific CTL response in PBC. Importantly, our data indicate that pre-treatment with either lactacystin or bafilomycin inhibits the PDC-E2 immune complex-induced CTL response. The processing and presentation of PDC-E2 by CD8(+)T cells is mediated by proteasomes and facilitated by Fcgamma receptor-mediated endocytosis. This data reflects another layer of interaction between components of the immune system in the development of autoimmunity. Further characterization of autoantigen uptake and processing may lead to potential therapeutic intervention.