采用荧光定量PCR溶解曲线法监测人TCR alpha链CDR3谱系漂移技术的初步探讨

目的:初步探讨荧光定量PCR溶解曲线分析技术监测人外周血T细胞TCR alpha链CDR3谱系漂移(单/寡/多克隆增生).方法:提取4例正常人、2例淋巴瘤型白血病患者PBMC中的总RNA,逆转录成cDNA,以32个人TCR alpha 链胚系可变区基因家族 (TRAV)设计上游引物,共同的TCR alpha 胚系链恒定区基因家族(TRAC)设计下游引物,荧光定量PCR(FQ-PCR)扩增32个TRAV基因各家族CDR3谱系,溶解曲线法分析各家族CDR3谱系的单/寡/多克隆增生.结果:正常人外周血T细胞TCR alpha链32个家族CDR3表达频率不一致,各家族PCR产物的溶解曲线谱型图(melting curve spectratyping)呈现熔点不同的CDR3多态性,为多克隆增生的高斯分布,2例淋巴瘤型白血病患者外周血T细胞TCR alpha链32个家族CDR3表达频率不一致,部分家族呈缺失状态,患者各家族PCR产物的溶解曲线谱型图上,多数家族为多克隆增生的高斯分布,但每个患者均出现数量不等的单克隆和寡克隆增生家族.结论:荧光定量PCR溶解曲线分析TCR alpha链CDR3谱系漂移技术方法稳定简便,能较好地监测正常人和临床样本外周血T细胞TCR alpha链CDR3谱系漂移(单/寡/多克隆增生).     

乙型肝炎患者治疗前后外周血CD4+ CD25+ Tregs TCR CDR3 谱系漂移特征分析

目的:探讨AHB 患者急性期及恢复期、CHB 患者恩替卡韦治疗前后外周血PBMC 中CD4+ CD25+ Tregs TCR CDR3 谱系漂移特征的变化。方法:采集4 例正常人、3 例AHB 患者(急性期和恢复期)及4 例CHB 患者恩替卡韦治疗前后外周抗凝静脉血,分离外周血PBMC;磁珠分选法分选CD4+ CD25+ Tregs,提取总RNA,逆转录合成cDNA;根据TCR β链24 个可变区基因(TRBV)家族设计相应的上游引物,并在茁链恒定区(BC)设计一条共用的FAM 荧光标记下游引物及对照引物。PCR 扩增出24 个包含完整CDR3 区的TRBV 家族的PCR 产物,电泳鉴定目的片段; PCR 产物送上海基康用毛细管电泳法进行基因扫描;用Peak Scanner Software v1.0 软件分析研究对象TRBV 家族CDR3 谱系特征;采用配对t 检验(paired-sample ttest)检测AHB 患者急性期及恢复期、CHB 患者恩替卡韦治疗前后TRBV 家族谱系漂移率差异。结果:3 例AHB 患者急性期呈现普遍谱系漂移的TRBV4、10、14、16、19 家族在恢复期多转变为正态的多峰谱型,AHB 患者恢复期外周血CD4+ CD25+ Tregs TRBV 家族CDR3 谱型漂移率显著低于急性期(t =9.456,P =0.011);TRBV8、11、13.2、15、16、18、20 在3 例CHB 患者抗HBV治疗前出现克隆增生,TRBV1、5.2、6、12、14、24 在3 例CHB 患者抗HBV 治疗后出现克隆增生。CHB 患者抗病毒治疗后TRBV家族CDR3 谱型漂移率高于治疗前(t =-0.666,P =0.553)。结论:AHB 患者急性期呈现谱系漂移的TRBV4、10、14、16、19 家族在恢复期多转变为正态的多峰谱型,推测这种转变可能与HBsAg、HBeAg 转阴相关。CHB 患者在治疗前TRBV8、11、13.2、15、16、18、20 家族克隆增生的Tregs 可能通过下调机体的细胞免疫应答,阻碍病毒清除;随着药物导致病毒载量的显著下降,TRBV1、5.2、6、12、14、24 家族克隆增生的Tregs 可能更有助于诱导机体出现免疫耐受,导致HBV 不能彻底清除。     

强直性脊柱炎患者外周血TCR Vα CDR3谱系基因扫描分析研究

目的:探讨强直性脊柱炎(AS)患者外周血T细胞受体α链可变区互补决定区3(TCR Vα CDR3)谱系多态性,为AS的免疫发病机制的研究提供实验基础。方法:采用反转录-聚合酶链反应(RT-PCR)扩增34个TCR Vα亚家族,经免疫扫描谱型技术分析AS患者外周血单个核细胞(PBMC)中T细胞TCR Vα CDR3的谱系漂移情况。结果:5例正常健康对照PB-MC TCR Vα CDR3谱型多数呈高斯分布。所有AS患者外周血T细胞均出现多个TCR Vα亚家族谱型的异常改变,异常峰型包括:单峰、寡峰/寡峰趋势、偏峰和不规则异常峰型。34个TCR Vα亚家族中,共有17个亚家族在少数患者中的扫描谱型呈单峰即单克隆增生。结论:AS患者PBMC TCR Vα CDR3谱系具有显著多态性,表明T细胞在AS免疫发病机理中扮演重要角色。单/寡克隆增生的T细胞有可能是AS发病中的自身反应性T细胞,将为AS的发病机制的进一步研究提供基础依据。     

抗病毒治疗对CHB患者外周血TCRβ链CDR3谱系的影响

目的:分析慢性乙型肝炎(CHB)患者抗病毒治疗前后T淋巴细胞受体(TCR)β链各家族互补决定区3(CDR3)谱系的变化,了解抗病毒治疗前后T细胞应答的变化。方法:采用荧光定量PCR(FQ-PCR)溶解曲线法对11例CHB患者抗病毒治疗前后外周血单个核细胞(PBMC)T淋巴细胞受体β链可变区(TCR BV)基因各家族CDR3谱系进行分析,了解抗病毒治疗前后T细胞应答的变化。分析TCR CDR3谱系与CHB患者血清病毒载量的关系。结果:11例CHB患者抗病毒治疗后多个TCR CDR3谱系均出现了不同程度偏移。低病毒载量组(HBV DNA≤104拷贝/ml)治疗后谱型偏移率显著高于高病毒载量组(HBV DNA≥105拷贝/ml)。结论:CHB患者抗病毒治疗后单寡谱型偏移率与治疗前血清HBV DNA的水平相关。     

不同HBV感染状态患者外周血CD4~+CD25~+Tregs TCR CDR3谱系漂移特征分析

目的探讨慢性HBV携带者、慢性乙型肝炎(chronic hepatitis B,CHB)及急性乙型肝炎(acute hepatitis B,AHB)这3种不同HBV感染状态下患者外周血中CD4~+ CD25~+调节性T细胞(T regulatory cells,Tregs)T细胞受体(T cell receptor,TCR)β链各家族互补决定区3(complementarity-determining region 3,CDR3)谱系漂移特征。方法采集3例正常人、5例慢性HBV携带者、12例CHB及5例AHB患者外周抗凝静脉血,分离外周血单个核细胞(peripheral blood mononuclear cell,PBMC);磁珠分选法分选CD4~+ CD25~+Tregs,提取总RNA,逆转录合成c DNA;根据TCRβ链24个可变区基因(TRBV)家族设计相应的上游引物,并在β链恒定区(BC)设计1条共用的FAM荧光标记下游引物及对照引物。PCR扩增出24个包含完整CDR3区的TRBV家族的PCR产物,电泳鉴定目的片段;PCR产物送上海基康用毛细管电泳法进行基因扫描;用Peak Scanner Software v1.0软件分析TRBV家族CDR3谱系特征。结果不同HBV感染状态下24个TRBV家族CDR3谱系图均呈现一个或者多个形态不一、数量不等的单峰、寡峰、偏峰谱型,其中一些家族表达极低或缺失,在1.5%琼脂糖凝胶电泳图上多数家族于预测范围大小处呈现1条模糊条带,部分家族出现清晰条带或无条带;对不同HBV感染者间各TRBV家族CDR3谱系偏移率进行比较发现:慢性HBV携带者中BV7谱系偏移率明显高于CHB及AHB患者(P均0.05),CHB患者中BV15谱系偏移率明显高于慢性HBV携带者及AHB患者(P均0.05),AHB患者中BV23谱系偏移率明显高于CHB及慢性HBV携带者(P均0.05)。CHB患者外周血CD4~+ CD25~+Tregs TRBV家族CDR3克隆增生总体异常率与HBV DNA载量呈正相关关系(r=0.576 5,P=0.049 8)。结论部分优势利用的TRBV家族可能在感染HBV后免疫耐受以及清除病毒中发挥重要作用。     

T-ALL及T细胞株相关TCR Vβ基因谱系和克隆性分析

目的了解T细胞-急性淋巴细胞白血病(T-ALL)患者外周血中的T细胞及T细胞株的TCR Vβ基因谱系及其克隆性增殖情况。方法利用RT-PCR方法扩增6个不同的T细胞株和6例初发未治T-ALL病人外周血单个核细胞中24个TCR Vβ基因的互补决定区3(CDR3)，PCR产物进一步经荧光标记和基因扫描分析CDR3长度而确定T细胞的克隆性，部分T细胞株的单克隆PCR产物进一步进行序列分析。结果与正常人外周血表达全部24个Vβ亚家族不同，6例T-ALL病人分别表达5～12个Vβ亚家族。6例病人均存在1个或多个Vβ亚家族的寡克隆或双克隆增殖T细胞，另外，还有一些Vβ亚家族多克隆模式发生改变，呈现寡克隆性增殖的趋势。T细胞株多显示为表达一个Vβ亚家族的单克隆T细胞，不同T细胞株的CDR3长度和序列不尽相同。结论T-ALL患者外周血T细胞的TCR Vβ谱系出现限制性改变，均可检测到克隆性增殖T细胞，尚需进一步鉴定其性质(肿瘤性或抗原特异性增殖)，对于检测微小残留病变和设计抗白血病独特型疫苗均有一定的意义。     

葡萄膜炎患者外周血TCR Vα谱系多态性分析

目的 探讨葡萄膜炎患者外周血T细胞受体α链可变区互补决定区3 (TCR Vα CDR3)谱系特点及多态性.方法 采用RT-PCR扩增葡萄膜炎患者外周血单个核细胞(PBMC)中TCR Vα 34个亚家族,经免疫扫描谱型技术分析34个亚家族谱型.结果 5例正常健康人PBMC TCR Vα CDR3谱型多数呈高斯分布,4例葡萄膜炎患者外周血T细胞均出现多个TCR Vα亚家族谱型的异常改变,异常峰型包括单峰、寡峰/寡峰趋势,偏峰和不规则异常蜂型.34个TCR Vα亚家族中,不同亚家族异常峰型出现的频率不同,非正态异常峰型出现频率较高的亚家族有Vα13和Vα17(均为3/4),而Vα1.1、Vα10、Vα20、Vα28和Vα28亚家族均未出现异常峰型.TCR Vα7在HLA-B27阴性的患者(U2)中出现异常峰型,在HLA-B27阳性的3个患者(U1、U3、U4)中并未出现这个亚家族的异常;TCR Vα13则相反,即在HLA-B27阳性的3个患者中均出现异常峰型,而在HLA-B27阴性的患者中正常.结论 葡萄膜炎患者PBMC TCR Vα CDR3谱系具有显著多态性特点,单/寡克隆增生的T细胞有可能是葡萄膜炎发病中的自身反应性T细胞.     

苯中毒工人外周血TCR Vβ克隆性T细胞利用特点

目的:分析苯中毒工人外周血中克隆性增殖T细胞及其CDR3序列的特点.方法:利用RT-PCR方法扩增11例苯中毒工人外周血单个核细胞中24个TCR Vβ基因的CDR3, 阳性产物进一步经荧光标记和基因扫描分析CDR3长度而了解其克隆性.结果:健康者外周血中可检测到24个Vβ亚家族, 11例苯中毒工人仅检测到2～10个Vβ亚家族.11例苯中毒工人均存在1个或多个Vβ亚家族T细胞出现寡克隆及寡克隆趋势.Vβ2、4、5、6和Vβ21的寡克隆T细胞出现频率较高.结论:苯中毒工人外周血TCR Vβ亚家族T细胞出现倾斜性分布和克隆性增殖, 这可能是机体苯中毒后所引起的特异性免疫反应.     

APL相关TCRVα6、Vα10和Vβ23寡克隆T细胞CDR3序列分析

目的:分析急性早幼粒细胞白血病(APL)患者外周m TCR Vα和Vβ克隆性增殖T细胞及CDR3序列特点.方法:利用RT-PCR法扩增1例APL患者外周血单个核细胞中29个TCR Vα基因和24个Vβ基因CDR3,阳性PCR产物进一步经荧光标记和基因扫描分析确定其CDR3长度,了解其克隆性;寡克隆的PCR产物再进行CDR3区序列分析.结果:该例APL患者外周血T细胞分别在TCR Vα6、Vα10和Vβ23亚家族中出现寡克隆性增殖T细胞,经序列分析显示TCR Vα6、Vα10和Vβ23亚家族基因序列分别为Vα6NJα17、Vα10NJα35和Vβ23NDβ1NJβ2.7,其CDR3区氨基酸序列分别为CAMRENSAGNK,YLCAGDELLWECA,CASSSKWAG-GTYEQY,该3个TCR基因已被GenBank收录(登陆号:EU544946、EU544947和EU647219).结论:APL患者外周血T细胞出现的TCR Vα6、Vα10和Vβ23克隆性增殖T细胞可能是机体对抗白血病细胞所引起的抗原特异性免疫反应;这3个独特TCR重排序列将进一步作为开展APL特异性免疫治疗研究提供资料.     

慢性乙型肝炎患者外周血CD8~+T细胞TCR Vβ基因亚家族克隆化的研究

目的:分析慢性乙型肝炎(CHB)患者CD8+T细胞TCR Vβ基因亚家族克隆化特征。方法:采用逆转录-聚合酶链反应(RT-PCR)扩增8例CHB患者外周血CD8+T细胞TCR Vβ基因22个亚家族的CDR3区,基因扫描技术对TCR Vβ亚家族的克隆化进行鉴定。结果:基因扫描显示所有8例CHB患者CD8+T细胞TCR Vβ基因亚家族均出现一个或一个以上单克隆或寡克隆增生。Vβ8、Vβ11、Vβ12出现单克隆增生的频率相对较高。8例健康者TCR Vβ基因亚家族均为多克隆。结论:CHB患者外周血CD8+T细胞TCR Vβ亚家族存在克隆性增生。     

Development of TCRB CDR3 length repertoire of human T lymphocytes

The third complementarity-determining region (CDR3) of TCR interacts directly with antigenic peptides bound to grooves of MHC molecules. Thus, it is the most critical TCR structure in launching acquired immunity and in determining fates of developing thymocytes. Since length is one of the components defining the CDR3 heterogeneity, the CDR3 length repertoires have been studied in various T cell subsets from humans in physiological and pathological conditions. However, how the CDR3 length repertoire develops has been addressed only by a few reports, including one showing that CDR3 of CD4 thymocytes becomes shorter during thymic development. Here, we explored multiple regulations on the development of the TCRB CDR3 length repertoires in the thymus and the peripheral blood. CDR3 length spectratyping was employed to examine thymocyte and peripheral T cell populations for their CDR3 length repertoires. We have found that repertoire distribution patterns depend on use of the BV gene. The BV-dependent patterns were shaped during thymic selections and maintained in the peripheral blood. Differences in the mean CDR3 length among different BV subsets were seen throughout lymphocyte development. We also observed that CDR3 was shortened in both CD4 and CD8 thymocytes. Of note, the degrees of the shortening depended on the CD4/CD8 lineage and on use of the BV gene. When expansions of peripheral T cell clones are negligible, no obvious difference was seen between mature thymocytes and peripheral lymphocytes. Thus, the TCRB CDR3 length repertoires are finely tuned in the thymus before the lymphocytes emigrate into the peripheral blood.     

Cloning of the IgM heavy chain of the bottlenose dolphin (Tursiops truncatus), and initial analysis of VH gene usage

Clones encoding the dolphin IgM heavy (micro) chain gene were isolated from a cDNA library of peripheral blood leukocytes. Genomic Southern blot analyses showed that the dolphin IGHM gene is most likely present in a single copy, and its sequence shows greatest similarity to those of the IGHM gene of the sheep, pig and cow, evolutionarily related artiodactyls. The transmembrane (TM) form of the IGHM chain was isolated by 3' RACE. While showing similarities to the TM regions of other mammalian IGHM chains, the highly conserved Ser residue of the CART motif is substituted with a Gly in the dolphin. In contrast to the pig and cow, which utilize only a single VH family, the dolphin expresses at least two distinct VH families, belonging to the mammalian VH clans I and III. At least two JH genes were identified in the dolphin. Some CDR3 regions of the dolphin VH are long (up to 21 amino acids), and contain multiple Cys residues, hypothesized to stabilize the CDR3 structure through disulfide bond formation.     

Clonal expansions of 6-thioguanine resistant T lymphocytes in the blood and tumor of melanoma patients

The identification of specific lymphocyte populations that mediate tumor immune responses is required for elucidating the mechanisms underlying these responses and facilitating therapeutic interventions in humans with cancer. To this end, mutant hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficient (HPRT-) T-cells were used as probes to detect T-cell clonal amplifications and trafficking in vivo in patients with advanced melanoma. Mutant T-cells from peripheral blood were obtained as clonal isolates or in mass cultures in the presence of 6-thioguanine (TG) selection and from tumor-bearing lymph nodes (LNs) or metastatic melanoma tissues by TG-selected mass cultures. Nonmutant (wild-type) cells were obtained from all sites by analogous means, but without TG selection. cDNA sequences of the T-cell receptor (TCR) beta chains (TCR-beta), determined directly (clonal isolates) or following insertion into plasmids (mass cultures), were used as unambiguous biomarkers of in vivo clonality of mature T-cell clones. Clonal amplifications, identified as repetitive TCR-beta V-region, complementarity determining region 3 (CDR3), and J-region gene sequences, were demonstrated at all sites studied, that is, peripheral blood, LNs, and metastatic tumors. Amplifications were significantly enriched among the mutant compared with the wild-type T-cell fractions. Importantly, T-cell trafficking was manifested by identical TCR-beta cDNA sequences, including the hypervariable CDR3 motifs, being found in both blood and tissues in individual patients. The findings described herein indicate that the mutant T-cell fractions from melanoma patients are enriched for proliferating T-cells that infiltrate the tumor, making them candidates for investigations of potentially protective immunological responses.     

Analysis of the CDR3 Length Repertoire and the Diversity of TCRα Chain in Human Peripheral Blood T Lymphocytes

Analysis of complementarity determining region 3 （CDR3） length of T lymphocyte receptors （TCRs） by immunoscope spectratyping technique has been used successfully to investigate the diversity of TCR in autoimmune diseases and infection diseases. In this study, we investigated the patterns of CDR3 length distribution for all 32 TCR AV gene families in human peripheral blood lymphocytes of four normal volunteers by the immunoscope spectratyping technique. It was found that PCR products exhibited an obscure band on 1.5% agarose gel electrophoresis. Each TCR AV family exhibited more than 8 bands on 6% sequencing gel electrophoresis. The CDR3 spectratyping of all TCR AV families showed a standard Gaussian distribution with different CDR3 length, and the expression frequency of CDR3 was similar among the gene families. Most of CDR3 in TCR AV family recombine in frame. However, some of the CDR3 showed out-of frame gene rearrangement. Additionally, we found that in some of TCR AV families there were 18 amino acid discrepancies between the longest CDR3 and shortest CDR3. These results may be helpful to further study the recombination mechanism of human TCR genes, the TCR CDR3 gene repertoire, and the repertoire drift in health people and disease state. Cellular ＆ Molecular Immunology.     

Third complementarity-determining region of mutated VH immunoglobulin genes contains shorter V, D, J, P, and N components than non-mutated genes

The third complementarity-determining region (CDR3) of immunoglobulin variable genes for the heavy chain (VH) has been shown to be shorter in length in hypermutated antibodies than in non-hypermutated antibodies. To determine which components of CDR3 contribute to the shorter length, and if there is an effect of age on the length, we analysed 235 cDNA clones from human peripheral blood of VH6 genes rearranged to immunoglobulin M (IgM) constant genes. There was similar use of diversity (D) and joining (JH) gene segments between clones from young and old donors, and there was similar use of D segments among the mutated and non-mutated heavy chains. However, in the mutated heavy chains, there was increased use of shorter JH4 segments and decreased use of longer JH6 segments compared to the non-mutated proteins. The overall length of CDR3 did not change with age within the mutated and non-mutated categories, but was significantly shorter by three amino acids in the mutated clones compared to the non-mutated clones. Analyses of the individual components that comprise CDR3 indicated that they were all shorter in the mutated clones. Thus, there were more nucleotides deleted from the ends of VH, D, and JH gene segments, and fewer P and N nucleotides added. The results suggest that B cells bearing immunoglobulin receptors with shorter CDR3s have been selected for binding to antigen. A smaller CDR3 may allow room in the antibody binding pocket for antigen to interact with CDRs 1 and 2 as well, so that as the VDJ gene undergoes hypermutation, substitutions in all three CDRs can further contribute to the binding energy.     

Composition and variation analysis of the TCR β-chain CDR3 repertoire in systemic lupus erythematosus using high-throughput sequencing

The ability of T lymphocytes to mount an immune response against a diverse array of pathogens is primarily conveyed by the amino acid (aa) sequence of the hypervariable complementarity-determining region 3 (CDR3) segments of the T cell receptor (TCR). In this study, we used a combination of multiplex-PCR, Illumina sequencing and IMGT/HighV-QUEST for a standardized analysis of the characteristics and polymorphisms of the T-cell receptor BV complementarity-determining region 3 (TCR BV CDR3) gene in peripheral blood mononuclear cells (PBMCs) from SLE patients and healthy donors (NC). We found the distributions of CDR3, VD indel, and DJ indel lengths to be comparable between the SLE and NC groups. The degree of clonal expansion in the SLE group was significantly greater than in the NC group, and the expression levels of 10 TRβV segments and 6 TRβJ segments were also significantly different in the SLE group. Regarding public T cell responses, 3CDR3 DNA sequences and 4 aa sequences were shared by all SLE patients and may serve as biomarkers for SLE disease risk, diagnosis and/or prognosis.     

Diverse T-cell receptor CDR3 length patterns in human CD4+ and CD8+ T lymphocytes from newborns and adults

T cells are essential in the initiation and maintenance of immune responses. Specific interaction between T cells and a presumptive antigen occurs through recognition of an MHC-peptide complex by the T-cell receptor (TCR). The complementarity-determining region (CDR) 3 of the TCR has direct contact with the peptide. Here we describe CDR3 length variability of six different TCRBV gene families of CD4+ and CD8+ umbilical cord (UC) and peripheral blood (PB) T cells. Amplified products spanning the TCR CDR3 regions from CD4+ PB, CD4+ UC and CD8+ UC blood T cells typically displayed Gaussian-like distributions. In contrast, profound and frequent perturbations were recorded in CD8+ PB lymphocytes, with a non-Gaussian pattern in more than half of the samples studied. A substantial portion of the perturbed CD8+ subsets were clonal or oligoclonal, as determined by CDR3-length restriction, TCRBJ gene usage and nucleotide sequencing. This implies that the conditions for shaping and maintenance of the peripheral TCR repertoire are profoundly different for CD8+ and CD4+ T cells.     

Selection of T cell receptor variable gene-encoded amino acids on the third binding site loop: a factor influencing variable chain selection in a T cell response

The 3′ end of the T cell receptor Vβ7.1 gene contains the five nucleotides CAAGA between the broadly conserved consensus sequence of nucleotides TGC/T GCC AGC AGC (which encode cysteine, alanine, serine and serine at positions 92–95 of the β chain) and the heptamer that signals rearrangement. These nucleotides are frequently preserved during gene rearrangement, resulting in the common presence of glutamine at position 96 and of aspartate or glutamate at position 97 of the Vβ7.1 chain CDR3 loop in peripheral blood lymphocytes. There is selection of Vβ7.1 and of the Vβ7.1 gene-encoded glutamate at position 97 of the β chain CDR3 loop in the cytotoxic T lymphocyte response to the HLA B2705-restricted influenza A nucleoprotein epitope SRYWAIRTR. Our results indicate that selection of Vβ7.1 gene-encoded amino acid residues on CDR3 loops may be one factor driving selection of Vβ7.1 in this response.     

Preferential utilization of the immature JH segment and absence of somatic mutation in the CDR3 junction of the Ig H chain gene in three X-linked severe combined immunodeficiency patients

Human severe combined immunodeficiency (SCID) includes an X-linkedSCID (XSCID) characterized by a complete absence of mature Tcells, hypogammaglobuilnemia and a normal or elevated numberof B cells. XSCID results from mutation in the IL-2 receptor(IL-2R) chain gene, which is thought to be involved in notonly IL-2R but also IL-4R and IL-7R mediated signals. To investigatethe VDJ recombination and Ig repertoire development in the absenceof the IL-2R chain, we intended to study the CDR3 junctionin peripheral blood B cells of three XSCID patients. A totalof 101 different CDR3 Junctions were cloned following polymerasechain reaction amplification of polyclonal peripheral bloodlymphocyte DNA. Sequence analysis of CDR3 Junctions revealedthat the primary antibody repertoire of the Ig H chain genewas assembled In a normal fashion. Among the J_H segments, overexpressionof J_H3 segments was significant in XSCID patients compared withage-matched controls. D segment usage in XSCID was very similarto that in age-matched controls. All of the XSCID J_H regionsexcept for two clones were equal to germline JJ_H genes, showinglittle or no evidence of somatic mutation. The results indicatethat the immature JJ_H segment is preferentially utilized andsomatic mutation is absent in the CDR3 Junction of the Ig Hchain gene of XSCID patients.     

Profiling the repertoire of T-cell receptor beta-chain variable genes in peripheral blood lymphocytes from subjects who have recovered from acute hepatitis B virus infection

The profile of T-cell receptor beta-chain variable （TRBV） genes usually skews in subjects with virus infection or cancer. The gene melting spectral pattern （GMSP） can be used to determine the profile of the TRBV gene family. To explore the portrait of the TRBV family in peripheral blood lymphocytes from subjects who have recovered from acute hepatitis B virus infection （AHI）, peripheral blood mononuclear cells （PBMCs） were separated and further sorted into CD4^＋ and CD8^＋ T-cell subsets. The molecular features of the TRBV complementary determining region 3 （CDR3） motifs were determined using GMSP analysis. When a GMSP profile showed a single peak, the monoclonally expanded TRBV gene was cloned and sequenced. Skewed expansions of multiple TRBV genes were observed among the CD4^＋ and CD8^＋ T-cell subsets and the PBMCs. The frequency of monoclonally expanded TRBV genes in the CD8^＋ T-cell subset was significantly higher than that of the CD4^＋ T-cell subset and the PBMCs. Compared to other members of the TRBV gene family, TRBV11, BV15 and BV20 were predominantly expressed in the repertoire of peripheral blood lymphocytes in recovered AHI subjects. The relatively conserved amino acid motifs of TRBV5.1 and BV20 CDR3 were also detected in the CD4^＋ and CD8^＋ T-cell subsets. These results demonstrate the presence of multiple biased TRBV families in recovered AHI subjects. TRBV11, BV15 and BV20, especially from the CD8＋ T-cell subset, may be relevant to the pathogenesis of subjects with AHh The preferentially selected TRBV5.1 and BV20 with the relatively conserved CDR3 motif may be potential targets for personalized treatments of chronic HBV infection.