Bridges S L, Lee S K, Koopman W J, Schroeder H W
Department of Medicine, University of Alabama, Birmingham 35294.
Arthritis Rheum. 1993 May;36(5):631-41.
To gain insight into mechanisms underlying local immune responses in rheumatoid arthritis (RA), we analyzed the utilization of variable-region heavy chain (VH), diversity (DH), and joining (JH) gene segments expressed in synovial tissue of a patient with RA.
An unrestricted complementary DNA (cDNA) library was generated from unselected cells extracted from synovial tissue obtained at the time of joint replacement. Southern blot analysis for VH, JH, and C gamma subclass utilization was performed on the first 50 C gamma- and JH-positive recombinants for which phage DNA was isolated. Eighteen of the clones were selected at random for sequence analysis. The VH gene segments were compared with an extensive database of germline and cDNA sequences.
All transcripts utilized gene segments from the VH1 (28%), VH3 (56%), and VH4 (15%) families. There was a predominance of JH4, JH5, and JH6 gene segment utilization. Fourteen of 18 randomly sequenced clones contained sufficient VH-region information for analysis. Eight (57%) were most closely related to VH gene segments that are preferentially expressed in human fetal liver or that encode antibodies with self-reactivity. The variable domains were heavily mutated, and replacement-to-silent substitution ratios (R:S ratios) in the antigen-binding domains (complementarity-determining regions [CDRs]) were disproportionately high. CDR3 lengths were quite variable, due to extensive N-region addition and 5'-exonuclease activity in the VH-DH-JH joins.
Plasma cells in this synovial tissue sample appear to express VH gene segments that are preferentially utilized during fetal development or in autoantibodies. The JH repertoire is similar to that seen in adult peripheral blood lymphocytes, but much different from that found during fetal development. The large number of somatic mutations and the high R:S ratios in the CDRs suggest an antigen-driven response.
为深入了解类风湿关节炎（RA）局部免疫反应的潜在机制，我们分析了一名RA患者滑膜组织中表达的重链可变区（VH）、多样性（DH）和连接（JH）基因片段的使用情况。
从关节置换时获取的滑膜组织中提取未分选的细胞，构建无限制互补DNA（cDNA）文库。对分离出噬菌体DNA的前50个Cγ和JH阳性重组体进行VH、JH和Cγ亚类使用情况的Southern印迹分析。随机选择18个克隆进行序列分析。将VH基因片段与广泛的种系和cDNA序列数据库进行比较。
所有转录本均使用来自VH1（28%）、VH3（56%）和VH4（15%）家族的基因片段。JH4、JH5和JH6基因片段的使用占优势。18个随机测序的克隆中有14个包含足够的VH区域信息用于分析。其中8个（57%）与在人胎肝中优先表达或编码具有自身反应性抗体的VH基因片段关系最为密切。可变区发生了大量突变，抗原结合域（互补决定区[CDR]）中的置换与沉默替换率（R:S比率）异常高。由于VH-DH-JH连接处广泛的N区添加和5'核酸外切酶活性，CDR3长度变化很大。
该滑膜组织样本中的浆细胞似乎表达在胎儿发育期间或自身抗体中优先使用的VH基因片段。JH基因库与成人外周血淋巴细胞中的相似，但与胎儿发育期间发现的有很大不同。CDR中大量的体细胞突变和高R:S比率表明存在抗原驱动的反应。
