Owens G P, Kraus H, Burgoon M P, Smith-Jensen T, Devlin M E, Gilden D H
Department of Neurology, University of Colorado Health Sciences Center, Denver 80262, USA.
Ann Neurol. 1998 Feb;43(2):236-43. doi: 10.1002/ana.410430214.
Multiple sclerosis (MS) cerebrospinal fluid and brain contain increased IgG and oligoclonal bands. Whether this oligoclonal and polyclonal IgG is directed against a disease-relevant antigen remains unknown. To distinguish between random activation versus a targeted B-cell response, we analyzed the IgG heavy chain variable region (VH) repertoire expressed in different lesions of an acute MS brain. To obtain a representative sample of the VH repertoire, we constructed directional complementary DNA libraries from plaque-periplaque messenger RNA and amplified VH regions from the library by nested polymerase chain reaction. When MS VH sequences were aligned to germline segments, about 60% of different VH sequences in the acute MS brain were VH4 germline segments, significantly greater than the known approximately 20% VH4 germline prevalence. Specific VH sequences were overrepresented and expressed at multiple plaque sites. Within some overexpressed populations, there were distinct sequence differences (clonal variants) indicative of clonal expansion. Alignment of VH sequences to their closest germline counterparts revealed extensive somatic mutation and the preferential accumulation of amino acid replacement mutations in complementarity determining regions. These observations suggest the limited B-cell response found in this acute MS brain was antigen driven.
多发性硬化症（MS）患者的脑脊液和大脑中IgG及寡克隆带增加。这种寡克隆和多克隆IgG是否针对与疾病相关的抗原仍不清楚。为了区分随机激活与靶向性B细胞反应，我们分析了急性MS脑不同病灶中表达的IgG重链可变区（VH）库。为了获得VH库的代表性样本，我们从斑块周围的信使RNA构建定向互补DNA文库，并通过巢式聚合酶链反应从文库中扩增VH区域。当将MS的VH序列与种系片段比对时，急性MS脑中约60%的不同VH序列为VH4种系片段，显著高于已知的约20%的VH4种系流行率。特定的VH序列过度表达并在多个斑块位点表达。在一些过度表达的群体中，存在明显的序列差异（克隆变体），表明克隆扩增。将VH序列与其最接近的种系对应序列比对，发现广泛的体细胞突变以及互补决定区中氨基酸替代突变的优先积累。这些观察结果表明，在这个急性MS脑中发现的有限B细胞反应是由抗原驱动的。
