Long-range effects in protein--ligand interactions mediate peptide specificity in the human major histocompatibilty antigen HLA-B27 (B*2701).

B*2701 differs from all other HLA-B27 subtypes of known peptide specificity in that, among its natural peptide ligands, arginine is not the only allowed residue at peptide position 2. Indeed, B*2701 is unique in binding many peptides with Gln2 in vivo. However, the mutation (Asp74Tyr) responsible for altered selectivity is far away from the B pocket of the peptide binding site to which Gln/Arg2 binds. Here, we present a model that explains this effect. It is proposed that a new rotameric state of the conserved Lys70 is responsible for the unique B*2701 binding motif. This side chain should be either kept away from pocket B through its interaction with Asp74 in most HLA-B27 subtypes, or switched to this pocket if residue 74 is Tyr as in B*2701. Involvement of Lys70 in pocket B would thus allow binding of peptides with Gln2. Binding of Arg2-containing peptides to B*2701 is also possible because Lys70 could adopt another conformation, H-bonded to Asn97, which preserves the same binding mode of Arg2 as in B*2705. This model was experimentally validated by mutating Lys70 into Ala in B*2701. Edman sequencing of the B*2701(K70A) peptide pool showed only Arg2, characteristic of HLA-B27-bound peptides, and no evidence for Gln2. This supports the computational model and demonstrates that allowance of B*2701 for peptides with Gln2 is due to the long-range effect of the polymorphic residue 74 of HLA-B27, by inducing a conformational switch of the conserved Lys70.     

人白细胞抗原HLA-B27在强直性脊柱炎中的临床意义

目的:探讨人白细胞抗原HLA-B27在强直性脊柱炎(AS)中的临床意义,及联合检测HLA-B27、C反应蛋白(CRP)和红细胞沉降率(ESR)的意义。方法:对18例AS患者、24例腰背痛患者和21健康体检者的血液标本进行HLA-B27、CRP、ESR检测,并比较其HLA-B27阳性率。结果:与健康对照组比较,AS组的3项指标均高于对照组(P0.05),且AS组HLA-B27阳性率均高于另外2组(P0.05)。结论:HLA-B27在强直性脊柱炎诊断中具有重要意义,与其具有高度疾病相关性,联合检测HLA-B27及CRP比联合检测HLA-B27及ESR更有利于疾病诊断。     

HLA-B2704重链胞外功能区基因片段的克隆表达及其生物学功能的初步鉴定

目的:克隆及可溶性表达 HLA-B*2704重链胞外功能区,并对其生物学功能进行初步鉴定.方法:以HLA-B 位点全长 cDNA 为模板,用 PCR-SSP 方法扩增 HLA-B*2704重链胞外区 cDNA,经测序鉴定后与 pET32a 可溶性核表达载体构建其重组核表达系统,并在大肠杆菌 BL21中表达,采用 Western 印迹及微量淋巴细胞毒阻断实验初步鉴定该蛋白的特异性及其生物学特性.结果:扩增出 HLA-B*2704重链胞外功能区 cDNA 片段,构建的HLA-B*2704 cDNA-pET32a 可溶性核表达载体可在大肠杆菌 BL21表达系统中得到较好表达,表达量约占菌体总蛋白的40%;通过 Western 印迹鉴定了表达蛋白的特异性;通过微量淋巴细胞毒阻断实验发现该重组蛋白具有生物活性并可特异性阻断 HLA-B27阳性细胞的微量淋巴细胞毒反应.结论:在大肠杆菌中表达了具有生物学活性的HLA-B*2704重链胞外功能区,为强直性脊柱炎的机理研究及特异性阻断药物的筛选提供了实验基础和新的靶标.     

Aberrant expression of HLA-B*3565Q is associated with a disrupted disulfide bond

The identification of expression variants is a challenge in HLA diagnostics. We here describe the identification of the novel allele HLA-B*3565Q. The serological HLA class I type, as determined by a lymphocytotoxicity test, was A11,24; B38; Bw4; Cw−; whereas PCR-sequence-specific primers resulted in A*11,*24, B*35,*38; Cw*12, thus suggesting the presence of a nonexpressed B*35 allele. To clarify the lack of serological HLA-B35 reactivity, exons 2 and 3 were sequenced following haplotype-specific amplification. At position 564 from the beginning of the coding region (exon 3), a transversion (C→G) was observed, which, at the amino acid level, results in a substitution from cysteine to tryptophane at position 164 of the mature polypeptide. Because this position is essential for the formation of a disulfide bond linking the cysteine residues at positions 101 and 164, which is strongly conserved in functional class I molecules of vertebrates, the disruption of this bond is very likely to be the reason for the lack of serological detectability. We later found the same novel allele in a second unrelated individual, of whom we were able to establish a lymphoblastoid cell line (B-LCL). Serological testing of this B-LCL indicated a very low aberrant expression of HLA-B*3565Q, which cannot be expected to be detected by standard serology techniques. Holger-Andreas Elsner and Peter A. Horn contributed equally to this work. The nucleotide sequence data reported in this paper have been published in the European Molecular Biology Laboratory, GenBank, and DNA Data Bank of Japan Nucleotide Sequence Database under the accession numbers AJ278746, AJ278747, and AJ879892. The name B*3565Q was officially assigned by the WHO Nomenclature Committee in December 2005. This follows the agreed policy that, subject to the conditions stated in the most recent Nomenclature Report (Marsh et al. 2005), names will be assigned to new sequences as they are identified. Lists of such new names will be published in the following WHO Nomenclature Report.     

携带HLA-B2704基因转基因小鼠技术的建立

应用显微注射法制备携带HLA B2 70 4基因的转基因小鼠 .对 2 86只昆明小鼠激素注射进行超排卵 ,采集受精卵 ,将含HLA B2 70 4基因的基因组DNA片段 (简称HLA B2 70 4DNA)显微注射到受精卵原核内 ,把注射存活的两细胞期受精卵移入假孕鼠的输卵管内使其发育产生后代 .用PCR方法进行F0代仔鼠及F1代仔鼠的转基因整合的检测 .利用RT PCR检测阳性鼠中的HLA B2 70 4转基因的表达 .采集了 84 11个卵 ,可注射卵 6 6 0 9个 ,其中注射存活的两细胞期受精卵 4 2 77个 ,卵的注射存活率为 6 4 7%.将卵移入 15 3只假孕鼠 ,其中 2 6只怀孕产仔 ,存活 10 1只 .在 10只F0代仔鼠基因组中有HLA B2 70 4基因整合 ,整合率为 9 9%.转基因阳性鼠F0代之间以及与正常鼠之间进行交配 ,产生的F1代仔鼠 78只 ,其中 15只为阳性 .阳性鼠的皮肤、结肠、睾丸和脾脏组织中均有HLA B2 70 4转基因mRNA的表达 .在HLA B2 70 4转基因阳性小鼠中 ,6只小鼠皮肤出现脱毛 ,1只小鼠的足部及足趾明显红肿 ,2只在脱毛同时明显畏光 ,1只出现腹泻 .结果表明 ,成功地建立了HLA B2 70 4的转基因小鼠技术 ,该小鼠类似强直性脊柱炎的小鼠模型 .     

Dissection and molecular analysis of alloreactive CD8+ T cell responses in allogeneic haematopoietic stem cell transplantation

We applied a cDNA expression screening procedure with cryopreserved non-clonal CD8+ T cell populations (Lennerz et al., Proc. Natl. Acad. Sci. USA 102:16013-8, 2005) to the identification of candidate antigens for graft-versus-host disease (GvHD) and graft-versus-leukaemia (GvL) effects in allogeneic haematopoietic stem cell transplantation (allo-HSCT). In a patient–donor model system with HLA class I disparities, we identified an HLA-B*44 mismatch allele, HLA-B*4405, as the dominant target of alloreactive T cells expanded in vitro from donor peripheral blood mononuclear cells (PBMC). HLA-B*4405-reactive T cells were detectable after multiple in vitro stimulations in the patient’s post-HSCT PBMC. In a patient–donor model with full HLA compatibility, the major target antigen of donor lymphocytes stimulated in vitro with the respective patient’s pre-HSCT PBMC was restricted by HLA-A*0201 and was encoded by TRIM22-442 C, a newly detected polymorphic allele of the tripartite motif family member TRIM22 (synonym: STAF50), preferentially expressed in cells of the haematopoietic system. An arginine(R)-to-cysteine(C) exchange at position 442 generated an immunogenic T cell epitope equivalent to a minor histocompatibility antigen (mHag). TRIM22-442C-specific T cells persisted long-term in the patient’s post-HSCT PBMC. Approximately, 1.3% of Caucasians carry TRIM22.442 C in association with HLA-A*0201. In particular, the knowledge of a large and diverse panel of such mHags may be crucial for further improvement of donor selection and adoptive T cell transfer strategies. The procedure applied herein will help to accelerate and facilitate their identification.     

Residue 116 determines the C-terminal anchor residue of HLA-B*3501 and -B*5101 binding peptides but does not explain the general affinity difference

 HLA-B^*3501 and -B^*5101 molecules, which belong to the HLA-B5 cross-reactive group, bind peptides carrying similar anchor residues at P2 and the C-terminus, but differences are observed in the preference for a Tyr residue at the C-terminus and the affinity of peptides. A recent study of HLA-B^*3501 crystal structure suggested that residue 116 on the floor of the F-pocket determines a preference for anchor residues at the C-terminus. In order to evaluate the role of the residue 116 in the peptide binding to both HLA-B^*3501 and HLA-B^*5101 molecules, we generated HLA-B^*3501 mutant molecules carrying Tyr at residue 116 (B^*3501–116Y) and tested the binding of a panel of nonamer peptides to the B^*3501–116Y molecules by a stabilization assay with RMA-S transfectants expressing the mutant molecules. The substitution of Tyr for Ser at residue 116 markedly reduced the affinity of nonamer peptides carrying Tyr at P9, while it enhanced that of nonamer peptides carrying Ile and Leu at P9. On the other hand, the affinity of peptides carrying aliphatic hydrophobic residues at P9 to B^*3501–116Y molecules was much higher than that to HLA-B^*3501 and HLA-B^*5101 molecules. These results indicate that residue 116 is critical for the structural difference of the F-pocket between HLA-B^*3501 and HLA-B^*5101 which determines the C-terminal anchor residues, while leaving other residues which differ between HLA-B^*3501 and HLA-B^*5101 may be responsible for the low peptide binding property of the latter. Received: 18 April 1997 / Revised: 18 September 1997     

CD8+T cells from a patient with colon carcinoma,specific for a mutant p21-Ras-derived peptide (GLY13→ASP), are cytotoxic towards a carcinoma cell line harbouring the same mutation

Several T lymphocyte clones (TLC), specific for a p21-Ras-derived peptide expressing a Gly¹³Asp mutation and of the CD8⁺ subtype, were generated from peripheral blood of a colon carcinoma patient. The TLC exerted cytotoxicity against an interferon- (IFN)-pretreated colon carcinoma cell line, HCT116, which harbours the Gly¹³Asp mutation and shares both HLA-A2 and HLA-B12(44) with the patient. This cytotoxic effect could be blocked by a monoclonal antibody (mAb) against CD8 molecules, as well as with a mAb against HLA class I molecules and a polyclonal antiserum against HLA-B12, identifying B12(44) as the antigen-presenting molecule. In growth-inhibition experiments, the growth of both IFN-pretreated and untreated target cells were strongly inhibited by the presence of the CD8⁺TLC. Together these data indicate that human cancer cells harbouring a spontaneousras mutation can process aberrant p21 Ras and express peptide/HLA-class-I complexes on their surface in sufficient density to be recognized by Ras-specific cytotoxic T lymphocytes.     

双通道TaqMan实时荧光PCR应用于别嘌呤醇不良反应相关基因HLA-B*58:01的检测与验证

摘要 目的：建立一种双通道TaqMan实时荧光PCR方法,应用于别嘌呤醇不良反应相关基因HLA-B*58:01的快速基因检测,并验证该方法的灵敏度、特异性、重复性及可靠性等性能指标。方法：针对HLA-B*58:01 等位基因序列设计引物和Taqman 探针,建立一种双通道TaqMan实时荧光PCR检测方法,收集陕西省人民医院、浙江大学医学院附属第二医院、浙江大学医学院附属邵逸夫医院三家医院收治的1158例临床诊断为痛风或血清尿酸高患者的外周血标本,采用双盲对照实验,分别采用双通道TaqMan实时荧光PCR法与已获审批的商业试剂盒共同检测所有标本,对比两种方法的检测结果进而评价该TaqMan实时荧光PCR方法的临床性能。结果：双通道TaqMan实时荧光PCR法特异性高,稳定可靠,可检测低至1 ng/?滋L的阳性样本;采用双通道TaqMan实时荧光PCR法与已获审批的商业试剂盒在1158份患者标本中检出的HLA-B*58:01阳性及阴性标本均相同,阳性标本147例,阴性标本1011例,该组患者HLA-B*58:01基因携带率为12.69%,两种方法符合率为100%（1158/1158）,两组实验结果数据采用SPSS分析P=1.000,差异无统计学意义。所有受检者HLA-B* 58:01携带率为12.69 % （147 /1158）。结论：双通道TaqMan实时荧光PCR可以作为一种快速、特异、灵敏的HLA-B*58:01的基因检测方法,用于别嘌呤醇用药前的相关不良反应风险评估。