T cell clonal expansions detected in patients with primary biliary cirrhosis express CX3CR1

The intrahepatic biliary destruction of primary biliary cirrhosis (PBC) appears secondary to a multi-lineage response that includes autoantibodies, biliary apotopes, and cellular responses. Although there has been considerable effort in defining the role and specificity of anti-mitochondrial autoantibodies, a major challenge has been the characterization of T effector pathways. This difficulty is due in part to the limitation of current technologies for directly isolating and characterizing autoreactive T cells from patients. Herein, we successfully demonstrate a novel technology for characterizing the surface phenotype of T cell oligoclonal expansions directly ex vivo. Using PBC as a prototypic disease we were able to detect clonal T cell expansions in 15/15 patients examined. Although the T cell expansions from different patients expressed different TCRVβ gene segments, the surface phenotype of the cells was the same. The clonal T cell expansions in PBC patients are CX3CR1⁺ Fas⁺ effector-memory T cells, a finding of particular importance given the known up-regulation of fractalkine on injured biliary epithelial cells (BEC). In contrast to the persistent aberrantly expanded T cells observed in the PBC patients, T cell expansions detected in response to a herpes viral infection were very dynamic and resolved over time. This protocol can be used to characterize T cell expansions in other autoimmune diseases.     

1月龄Balb/c小鼠胸腺、脾脏、肝脏、小肠和血液TRBV-TRBJ1-1 CDR3谱型分析

目的初步分析1月龄Balb/c小鼠胸腺、脾脏、肝脏、小肠和血液中TRBV-TRBJ1-1 CDR3谱型特征。方法提取1月龄Balb/c小鼠胸腺、脾脏、肝脏、小肠和血液样本的总RNA,逆转录成cDNA,以22条TRBV基因家族为上游引物,共同的TRBJ1-1基因为下游引物(荧光标记),PCR扩增包含完整CDR3区片断,毛细管电泳激光DNA扫描技术分析CDR3谱型的长度和多态性。结果胸腺样本毛细管电泳激光扫描图呈现标准的中间高两端低的多态性分布;各家族CDR3区最长和最短比较,多数为相差8～15个氨基酸的谱型分布。脾脏、肝脏、小肠、血液样本扫描图显示多数家族呈多态性分布,但均出现数量不等的单峰、寡峰、偏峰、低峰;多数家族表现为相差3～13个氨基酸的谱型分布,部分家族在预测大小位置无对应峰型。结论 1月龄Balb/c小鼠胸腺中基本包含TCR基因随机重排的多种克隆性T细胞;脾脏、肝脏、小肠、血液表现为单、寡、多克隆形式的T细胞分布,部分家族T细胞缺失,本实验结果可为进一步研究Balb/c小鼠的T细胞发育、分布、应答及CDR3谱型与疾病关系提供方法和基础。     

Detection of low-frequency human antigen-specific CD4(+) T cells using MHC class II multimer bead sorting and immunoscope analysis

MHC class II tetramers are attractive tools to study antigen-specific CD4(+) T cell responses in various clinical situations in humans. HLA-DRA1*0101/DRB1*0401 MHC class II heterodimers were produced as empty molecules using the Drosophila melanogaster expression system. Peptide binding experiments revealed that these molecules could be loaded efficiently with appropriate MHC class II tumor epitopes. Interestingly, MHC class II tetramer staining was influenced by modifications in membrane lipid rafts, and could in itself induce activation changes of stained CD4(+) T cells at 37 degrees C. In order to increase the threshold of detection of poorly represented peripheral antigen-specific CD4(+) T cells, we combined cell sorting using MHC class II multimer beads together with TCR analysis using the immunoscope technology. This strategy greatly increased the sensitivity of detection of specific CD4(+) T cells to frequencies as low as 4 x 10(-6) among peripheral blood mononuclear cells. Such a combined approach may have promising applications in the immunomonitoring of patients under vaccination protocols to tightly follow induced antigen-specific CD4(+) T cells expressing previously identified TCR.     

Analysis of the CDR3 length of TCR alphabeta T cells in the peripheral blood of patients with chronic hepatitis B.

To clarify the characteristics of TCR alphabeta T cells in the peripheral blood of patients with chronic hepatitis B (CHB), we investigated the patterns of Complementarity Determining Region3 (CDR3) length distribution for all 24 TCR BV gene families and 32 TCR AV gene family in the peripheral blood lymphocytes of two patients with CHB and two healthy controls by immunoscope spectratyping technique. We found that the profiles of CDR3 length distribution for all TCR AV and TCR BV family showed Gaussian distribution (the polyclonal TCR alphabeta T cells) in healthy controls, however, the restricted usage of TCR BV and TCR AV family (the oligoclonal TCR alphabeta T cells) has been monitored in two CHB patients, furthermore, the oligoclonal TCR alphabeta T cells showed the different CDR3 sequences and length, it might be correlated to the different epitope of hepatitis B virus (HBV) or the different HLA type of the patients. Detailed analysis of the CDR3 length of TCR alphabeta T cells might be interesting to light on the further study of the individualized immunotherapy of CHB and the further research of the new T lymphocyte epitope vaccine of HBV.     

慢性乙型肝炎患者外周血T淋巴细胞受体谱系分析及互补决定区3序列测定

目的从新的角度探讨慢性乙型肝炎（CHB）炎症活动期外周血T淋巴细胞克隆性增生情况，了解T淋巴细胞免疫应答在CHB发病机制中的状态及作用。方法利用逆转录聚合酶链反应（RT-PCR）扩增T淋巴细胞受体（TCR）β链V区基因各家族（BV），并采用免疫指纹技术（immunoscope）对4名健康献血员及8例处于炎症活动期CHB患者外周血TCR BV家族基因的优势利用情况及克隆性增生T淋巴细胞β链互补决定区3（CDR3）序列进行分析。结果4名健康献血员外周血T淋巴细胞TCR BV家族CDR3谱型均呈正态分布，而8例CHB患者均出现一个或多个TCR BV家族单克隆或寡克隆性增生。对克隆性增生T淋巴细胞β链CDR3区序列测定证实存在不同的CDR3序列。结论CHB活动期外周血T淋巴细胞存在明显克隆性增生，进一步提示T淋巴细胞免疫应答可能参与CHB的发病过程，且可能有多个病毒抗原表位参与了细胞免疫应答。     

T cell repertoire in DQ5-positive MuSK-positive myasthenia gravis patients

Myasthenia gravis (MG) is a prototypical antibody-mediated disease characterized by muscle weakness and fatigability. Serum antibodies to the acetylcholine receptor and muscle-specific tyrosine kinase receptor (MuSK) are found in about 85% and 8% of patients respectively. We have previously shown that more than 70% of MG patients with MuSK antibodies share the HLA DQ5 allele. The aim of the present study was to analyze the T cell receptor (TCR) repertoire specific for recombinant human MuSK protein. We used the CDR3 TRBV-TRBJ spectratyping (immunoscope) to analyze the T cell response to MuSK from 13 DQ5+ MuSK-MG patients and from 7 controls (six DQ5+ MuSK negative subjects and one DQ5− DQ3+ MuSK positive patient). DQ5+ MuSK-MG patients but not controls used a restricted set of TCR VJ rearrangements in response to MuSK stimulation. One semiprivate (TRBV29-TRBJ2.5) rearrangement was found in 5/13 patients, while 4 other semiprivate (one in TRBV28-TRBJ2.1 and in TRBV3-TRBJ1.2, and two in TRBV28-TRBJ1.2) rearrangements were differently shared by 4/13 patients each and were absent in controls. When we sequenced the TRBV29-TRBJ2.5 rearrangement, we obtained 26 different sequences of the expected 130 bp length from 117 samples of the 5 positive patients: two common motifs GXGQET/TEHQET were shared in 4 patients as semiprivate motifs. Thus, the MuSK-specific T-cell response appears to be restricted in DQ5+ MuSK-MG patients, with a semiprivate repertoire including a common motif of TRBV29. This oligoclonal restriction of T cells will allow the identification of immunodominant epitopes in the antigen, providing therefore new tools for diagnosis and targeted therapy.     

TCR β链CDR3谱序与疾病研究概况及进展

近年来,T细胞受体（TCR）互补决定区（CDR）和机体的生理、病理关系研究取得了较大的进展,尤其是在超抗原作用的感染性疾病、自身免疫性疾病、肿瘤等疾病状态下,TCRB链CDR3谱型能很好地反映T细胞的功能,通过TCRβ链CDR3谱型来研究克隆性和寡克隆性增生T细胞,可了解T细胞免疫与疾病发生发展的关系,指导疾病的诊断及免疫治疗,同时可了解正常情况下T细胞的发生和发展情况。