T 细胞受体δ、γ基因在小儿急性白血病中的变化

本文在细胞形态,表面抗原分析的基础上,对20例小儿急性白血症细胞进行TCRδ和γ基因结构的分析。11例属分化早期的白血病中有9例发生TCRδ基因的重排和缺失,其中5例也有TCRγ基因的重排。在5例属非淋巴细胞系的白血病中有3例发生TCRδ基因的重排.3例粒细胞性白血病细胞的TCR基因(δ和γ)均为胚系。有一例细胞表型仅有CD_2表达的白血病细胞,其TCR 基因(δ和γ)也为胚系。结果还显示:TCRδ基因结构发生变化的白血病细胞均有CD_(10)抗原表达。研究提示:TCRδ基因的重排不显示严格的细胞特异性,但是TCR 基因的变化与淋巴细胞系白血病细胞某些表面抗原的表达存在某种联系。     

多重PCR检测急性非淋巴细胞白血病IgH及TCRVγΙ-Jγ基因重排

目的:为进一步了解急性非淋巴细胞白血病(ANLL)病人基因重排情况。方法:应用多重PCR技术检测41例ANLL病人IgH及TCRVγIJγ基因重排。结果:26.8%(11/41)ANLL病人存在IgH或/和TCRVγIJγ基因重排,3例病人同时存在IgH和TCRVγIJγ基因重排;基因重排阳性ANLL治疗缓解率低于重排阴性ANLL病人(P<0.05)。结论:①IgH或TCR基因重排并非局限于淋巴细胞白血病,也可发生于部分ANLL病人;②多重PCR技术可以一次PCR扩增同时检测两种重排基因,更适于临床推广应用。     

不同发育阶段胸腺细胞表达不同类型

MHC 约束性T 细胞识别特异抗原的结构(TCR)由二条糖酰化多肽链(α、β)组成,并通过共价键与CD_3联结。近年发现,由γ、δ异二聚体组成的TCR 分布于不成熟胸腺细胞、外周血T 细胞、树状突上皮细胞(DEC)、囊上皮内的淋巴细胞等,其功能尚未完全明了,分析发育过程中γ、δ基因重排与表达有助于阐明它在TCR 功能中的协调配合作用。据此,本文分析胎胚、新生、成年小鼠胸腺细胞γδTCR 的多样性。将C_(57)BL/6、BALB/C 小鼠胸腺细胞用抗-L_3T_4单抗、抗-Lyt_2单抗及兔补体处理后获得CD_4~-、CD_8~-(双阴性、DN)胸腺     

血液系统肿瘤患者外周血细胞IgH基因和TCRγ基因的检测及意义

检测各种血液系统肿瘤患者外周血细胞免疫球蛋白重链基因 (IgH )和T细胞受体γ基因 (TCRγ )克隆性重排并探讨其意义。通过多聚酶链式反应 (PCR )方法检测 32例非霍奇金淋巴瘤 (NHL )、 18例急性髓性白血病 (AML )、 2 4例多发性骨髓瘤 (MM )、 8例急性淋巴细胞白血病 (ALL )及 6例慢性淋巴细胞白血病 (CLL )患者外周血细胞IgH及TCRγ克隆性基因重排。结果表明 ,NHL、AML、MM、ALL及CLL患者中IgH克隆性重排率分别为 37 5 0 %、 2 2 2 2 %、 83 33%、 12 5 0 %和 16 6 7% ;TCRγ基因克隆性重排率分别为 6 2 5 0 %、 5 0 0 0 %、 5 4 17%、 5 0 0 0 %及 5 0 0 0 %。在B型、T型NHL中 ,IgH克隆性重排率分别为 31 5 8%及 6 6 6 7% ;TCRγ克隆性重排率分别为 47 37%及 6 6 6 7%。AML中IgH克隆性重排阳性者的初治完全缓解率(CR ) (5 0 0 0 % )与IgH重排阴性的初治CR率 (5 0 0 0 % )无显著差异 (P >0 0 5 )。TCRγ克隆性重排阳性者与阴性者的初治CR率 (均为 44 44 % )亦无显著差异 (P >0 0 5 )。IgH及TCRγ基因克隆性重排不具有细胞谱系的特异性 ,但通过检测外周血IgH、TCRγ克隆性基因重排对NHL有辅助诊断意义 ,并且可作为监测微小残留病壮 (MRD )的手段。     

TCRγδ—是多余的T细胞亚群,还是免疫系统的特殊成分?

免疫学家在研究TCRαβ介导免疫识别的发育及结构的同时发现了一类新的T细胞亚群,它既不同于CD_8~+溶细胞性TCRαβ细胞,又不同于CD_4~+辅助性TCRαβ细胞,它由二硫键联结γ-和δ-基因产物(γ、δ键)组成。笔者近几年来着重研究TCRαβ细胞的胚系发生、多样性及其分子结构。众所周知,TCRγ基因是Tonegawa 等在寻求TCRαβ二聚体中α基因重排时发现的,γ基因虽可从TCRαβ细胞中分离到,但其编码的蛋白质并不参与TCRαβ细胞的功     

用单克隆抗体和基因扩增技术研究淋巴细胞白血病细胞起源

本研究采用系列单克隆抗体免疫酶方法(APAAP法)和体外基因扩增聚合酶链反应(PCR)技术,通过检测白血病细胞表面分化抗原及免疫球蛋白重链(IgH)和T细胞受体(TCR)γ、δ 基因重排,研究35例淋巴细胞白血病细胞起源。结果表明,20例表达B细胞表面标记,其中B-ALL15例,     

非霍奇金淋巴瘤的IgH和TCRδ基因重排

目的：探讨非霍奇金淋巴瘤（NHL）免疫球蛋白重链（IgH）和T细胞受体δ链（TCRδ）基因重排情况。方法：用半重叠式聚合酶链反应（PCR）方法检测IgH及TCRδ基因重排。结果：57例NHL中41例（72％）发生IgH基因重排，30例（53％）出现TCRδ基因重排。结论：检测克隆性基因重排可以作为诊断NHL有效基因标志，NHL中存在系列不忠实现象。     

IgH、TCR-γ基因重排与免疫组化诊断非霍奇金淋巴瘤的价值

目的　探讨基因重排与免疫组化在诊断非霍奇金淋巴瘤(non Hodgkin’slymphoma,NHL)中的价值。方法　对131 例NHL的石蜡包埋组织进行免疫组化和基因重排检测。结果　60例B细胞NHL中51例IgH基因重排检测为阳性,阳性率 85%;50例T细胞NHL中38例TCR -γ基因重排检测为阳性,阳性率76%;HE形态学和免疫组化分型诊断率为84%(110 例),加用IgH和TCR -γ基因重排,分型诊断率达94.6%(124例),两分型诊断率差异有显著性(P<0.05)。6例巨大淋巴结 增生和3例血管免疫母细胞性淋巴结病IgH和TCR -γ基因重排检测均为阴性。基因重排与形态学和免疫组化结果不相符的 病例有7例。结论　联合运用免疫组化和基因重排技术,可提高NHL的分型诊断率。     

γ/δT细胞抗原受体与一种新的具丝裂原作用的anti-δ抗体结合后产生的信号传导

近来在人外周血中发现有少数T 细胞带有一种不同于Tiαβ-CD_3的T 细胞抗原识别受体(TCR)。这种TCR 是由γ、δ多肽链和CD_3分子形成的复合物。同时在先天性无胸腺的小鼠和免疫缺陷的病人中发现有高水平的γ/δ-TCR~+细胞存在。这种TCR 也存在于胸腺细胞和一些肿瘤细胞膜上。γ/δ-TCR~+细胞功能尚不明确,它与具MHC 限制性的细胞毒作用和γIFN 的产生无关。基因研究发现在T 细胞分化早期,γ基因重排较α、β基因重排为早,提示γ/δ-TCR 在T 细胞发育中     

CML急变的Ig和TCR基因双重排

免疫球蛋自(Ig)和T细胞受体(TCR)基因重排可分别作为B细胞系和T细胞系的遗传学标记。约25%ALL,甚至AML,尤其是末端转脱氧核苷酸酶(TdT)阳性AML可有Ig和TCR基因双重排。CML急淋变多数源于有Ig基因重排的B细胞克隆,部分起源于有TCR基因重排的T细胞克隆。本文首次报告一例有IgH和TCR(β、δ)基因双重排,慢性期长达7年多的急淋变Ph~+CML。     

Acetaldehyde-induced mutation at the hprt locus in human lymphocytes in vitro

Acetaldehyde (Aa) induces chromosomal aberration and sister chromatid exchange in a variety of test systems, but has not previously been evaluated for its ability to induce gene mutation in mammalian cells. We have studied the mutagenic effect of Aa at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus in human lymphocytes in vitro by using the T-cell cloning technique and selection of mutant cell clones in medium containing thioguanine. Cells treated with 1.2-2.4 mM Aa for 24 hr or 0.2-0.6 mM Aa for 48 hr showed a dose-dependent decrease of cell survival and a 3- to 16-fold increase of the mutant frequency. The inverse relationship between cell survival and mutant frequency was linear down to a relative survival of 15%, and showed a similar slope in the 24-hr and 48-hr treatment experiments. Forty-one mutant T-cell clones derived from cultures treated with 1.2 or 2.4 mM Aa and 15 from untreated controls were expanded for DNA extraction and Southern blot analysis to study deletion mutation using a full length hprt cDNA probe, and clonal identity on the basis of T-cell receptor rearrangements. In the culture with a 16-fold increase of mutant frequency, 4 out of 10 independent mutants (40%) showed partial deletions extending beyond the 3' coding sequences of the hprt gene. Two of 22 independent mutants derived from the other treated cultures with at most a 6-fold increase of mutant frequency, and 1 of 11 independent control clones showed rearrangement of the hprt gene, none of which affected the 3'-end of the hprt gene. These results show that Aa is capable of inducing gene mutation at the hprt locus in human cells, and suggest that deletion mutation affecting the 3'-end of the gene may be a major type of Aa-induced mutation of this locus.     

Gross Rearrangement Breakpoint Database (GRaBD)

Translocations and gross gene deletions are an important cause of both cancer and inherited disease. Such DNA rearrangements are nonrandomly distributed in the human genome as a consequence of selection for growth advantage and/or the inherent potential of some DNA sequences to be particularly susceptible to breakage and recombination. The Gross Rearrangement Breakpoint Database (GRaBD; http://www.uwcm.ac.uk/uwcm/mg/grabd/) was established primarily for the analysis of the sequence context of translocation and deletion breakpoints in a search for characteristics that might have rendered these sequences prone to rearrangement. GRaBD, which contains 397 germline and somatic DNA breakpoint junction sequences derived from 219 different rearrangements underlying human inherited disease and cancer, is the only comprehensive collection of gross gene rearrangement breakpoint junctions currently available.     

High frequency of EBV association and 30-bp deletion in the LMP-1 gene in CD56 lymphomas of the upper aerodigestive tract

Natural killer (NK)/T-cell lymphomas are frequently associated with Epstein-Barr virus (EBV), and usually lack TCR gene rearrangement. Studies from Asia have reported frequent deletion in the LMP-1 gene in EBV-associated nasopharyngeal carcinoma (NPC). The present study aims to investigate LMP-1 and TCRgamma gene status in upper aerodigestive tract lymphomas. A total of 43 cases were classified into T-, B-, and NK/T-cell tumors based on the phenotype expressions of CD3(+)/CD20(-)/CD56(-), CD3(-)/CD20(+)/CD56(-), and CD3(+)/CD20(-)/CD56(+), respectively. The presence of EBV in the tumor was confirmed by EBV early RNA-in situ hybridization. LMP-1 gene deletion and TCR gamma gene rearrangement were analyzed by polymerase chain reaction on paraffin-embedded tissues. There were 20 NK/T-, eight T-, and 15 B-cell phenotype lymphomas in the present series, and EBV was detected in 19 (95%), two (25%), and three (20%) cases in the respective groups. All EBV+ cases carried 30-bp deletion in the LMP-1 gene, and two of the NK/T-cell cases were infected by both the wild type and deleted strains. Five (25%) of the NK/T-cell phenotype lymphomas showed rearranged TCR gamma gene. The present study revealed a high frequency of EBV association, and a high frequency of 30-bp deletion in the LMP-1 gene in the virus in the present series of lymphoma. The NK/T-phenotype lymphomas are comprised of both NK-cell and cytotoxic T-lymphocyte-derived tumors.     

A novel double deletion underscores the importance of characterizing end points of the CFTR large rearrangements

Large genomic rearrangements in patients with cystic fibrosis (CF) account for up to 16–24% of CF alleles negative for point mutations in European populations. Herein, we identified a new large rearrangement removing exon 19 in a young CF patient, who hitherto harbored only the F508del mutation. By using LightCycler technology, we successfully and rapidly delineated the deletion end points by determining the relative copy number of a set CFTR sequence from introns 18 to 19. Fine mapping of the sequences bordering its break points was achieved using direct sequencing. We reported the first complex CFTR rearrangement containing two successive deletion events putatively linked. We evidenced the presence of short direct repeats in the vicinity of the deletions suggesting a possible replication slippage model. In this report, we also discussed the putative molecular mechanism and consequences of this complex gene rearrangement, unprecedented in CF. This complex deletion illustrates the importance of delineating the genomic rearrangement to improve our knowledge of the CFTR mutational spectrum and to better understand the molecular mechanism controlling the CFTR expression.     

联合间期和中期荧光原位杂交检测发现11q23异常伴D13S319缺失急性髓系白血病一例

目的对1例出现11q23异常伴D13S319缺失的罕见急性髓系白血病(acute myeloid leukemia,AML)患者进行多途径细胞遗传学分析,为诊断、治疗及预后分层提供依据。方法应用G+R显带技术对患者24 h培养后的中期分裂相进行染色体核型分析,联合分裂间期和中期荧光原位杂交(fluorescence in situ hybridization,FISH)技术对患者染色体的特定位点进行检测,明确复杂易位和微小缺失片段。结果患者存在混合系白血病基因(mixed lineage leukemia,MLL)重排,形成了MLL-AF10融合基因,并伴有13号染色体D13S319位点的缺失。结论MLL基因重排合并D13S319位点缺失在急性白血病中是否具有双重打击效应应引起临床的重视。在AML患者核型中发现13q-、del(13)(q14)、-13或der(13)任意一种克隆性异常时,应行FISH检测论证及明确缺失片段的大小,以便进行靶向治疗。     

Maternal complex chromosome rearrangement ascertained through a del (13)(q12.1q14.1) detected in her mildly affected daughter

A maternal complex chromosome rearrangement (CCR) involving chromosomes 2, 13, and 20 was ascertained in a normal female through the diagnosis of a deletion of 13q in her daughter. The child has mild clinical features and developmental delay consistent with proximal deletions of 13q that do not extend into band q32 and a del(13)(q12q14.1) that does not involve the retinoblastoma locus by FISH. Maternal studies by GTG banding and FISH showed a complex karyotype with bands 13q12.3→13q12.1::20p13 translocated to 2p13 and bands 2pter→2p13::13q12.3→13q14.1 translocated into band 20p13. This would be the first report of an interstitial deletion of 13q inherited from a parental complex chromosome rearrangement. © 2001 Wiley‐Liss, Inc.     

Identification of critical regions for clinical features of distal 10q deletion syndrome

Array comparative genomic hybridization studies were performed to further characterize cytogenetic abnormalities found originally by karyotype and fluorescence in situ hybridization in five clinical cases of distal 10q deletions, including several with complex cytogenetic rearrangements and one with a partial male-to-female sex-reversal phenotype. These results have enabled us to narrow the previously proposed critical regions for the craniofacial, urogenital, and neuropsychiatric disease-related manifestations associated with distal 10q deletion syndrome. Furthermore, we propose that haploinsufficiency of the DOCK1 gene may play a crucial role in the pathogenesis of the 10q deletion syndrome. We hypothesize that alteration of DOCK1 and/or other genes involved in regulation and signaling of multiple pathways can explain the wide range of phenotypic variability between patients with similar or identical cytogenetic abnormalities.     

Detection of cystic fibrosis transmembrane conductance regulator (CFTR) gene rearrangements enriches the mutation spectrum in congenital bilateral absence of the vas deferens and impacts on genetic counselling

BACKGROUND: Mutations in the cystic fibrosis (CF) transmembrane conductanceregulator (CFTR) gene have been widely detected in infertilemen with congenital bilateral absence of the vas deferens (CBAVD).Despite extensive analysis of the CFTR gene using varied screeningmethods, a number of cases remain unsolved and could be attributableto the presence of large gene rearrangements, as recently shownfor CF patients. METHODS: We carried out a complete CFTR gene study in a group of 222CBAVD patients with strict diagnosis criteria and without renalanomaly, and searched for rearrangements using a semi-quantitativeassay in a subgroup of 61 patients. RESULTS: The overall mutation detection rate was 87.8%, and 82% of patientscarried two mutations. Ten out of the 99 different mutationsaccounted for 74.6% of identified alleles. Four large rearrangementswere found in patients who already carried a mild mutation:two known partial deletions (exons 17a to 18 and 22 to 23),a complete deletion and a new partial duplication (exons 11to 13). The rearrangements accounted for 7% of the previouslyunknown alleles and 1% of all identified alleles. CONCLUSIONS: Screening for rearrangements should be part of comprehensiveCFTR gene studies in CBAVD patients and may have impacts ongenetic counselling for the patients and their families.     

Frequent deletion of the transgene in T cell receptor {beta} chain transgenic mice

TCR V_ß8.1 transgenic mice were generated using a genomicTCR V_ß gene construct under the control of its promoterand enhancer. Among three lines of transgenic mice, one lineexpressed the transgenic TCR on only 70% of peripheral T cells,while the other two lines expressed it on almost all matureT cells. T cells which lacked expression of the transgenic TCRß chain expressed endogenous TCR ß chains.The molecular basis underlying the lack of transgene expressionin T cells of this line of transgenic mice was investigated.The transgenic TCR^– cells were isolated by two methods.First, Thy-1⁺ V_ß8.1/8.2^– cells were purifiedfrom peripheral T cells using cell sorting. Second, transgenicTCR^– T cell clones were established. In both cases, Southernblotting indicated that V_ß8.1^– T cells had deletedthe transgenic TCR gene. Thus, deletion of the transgenic TCRcan occur in a high proportion of T cells, which allows rearrangementand expression of endogenous TCR ß chains.     

Fragile X syndrome and deletions in FMR1: New case and review of the literature

The fragile X syndrome phenotype of mental retardation is almost always caused by abnormal CGG trinucleotide amplification within the FMR1 gene. Occasionally fragile X syndrome results from point mutations or deletions within or around the FMR1 locus. We have identified a mentally retarded African American male with typical fragile X phenotype and a 300–400 base pair intragenic deletion near the CGG repeat segment, present in his peripheral blood lymphocytes with no apparent mosaicism. His mother, who is not retarded, has a full FMR1 CGG expansion mutation with 700–900 repeats. A review of 23 published cases with FMR1 gene deletions shows full FMR1 mutation in the mother of only 1 other propositus, a male with FMR1 full mutation/premutation/deletion mosaicism of his cultured skin fibroblasts and peripheral blood lymphocytes. The various deletions within FMR1 and their clinical significance are reviewed. Am. J. Med. Genet. 72:430–434, 1997. © 1997 Wiley-Liss, Inc.