Wu H Y, Kaartinen M
Department of Bacteriology and Immunology, University of Helsinki, Finland.
Scand J Immunol. 1995 Jul;42(1):52-9. doi: 10.1111/j.1365-3083.1995.tb03625.x.
A biopsy specimen from a patient with follicular lymphoma was divided into two fragments. DNA was extracted from one fragment and a 1.2 kb region of the functional heavy chain (IgH) gene was amplified, cloned and sequenced (eight clones). From the other fragment a cell line (HF-1) was started. The IgH gene region was amplified from the cell line, and sequenced without cloning. The nine sequences obtained could be arranged into a genealogical tree where the individual sequences differed from the deduced ancestor by 16-29 single nucleotide changes, some also by an insertion and/or a deletion. It is apparent that the sequence alterations were caused by somatic mutations during the growth of the lymphoma. The comparison of the sequences with two published (allelic) germline sequences of the human JH region showed approximately 20% non-homology. The differences included five additional multinucleotide insertion/deletion changes, the longest of them a 101-nucleotide insertion. Two long insertions were homologous to the adjacent germline sequences. We propose that most of the changes observed, including long deletions and insertions, represent or are linked to somatic hypermutation events of the Ig gene type. Although in a few cases large deletions and insertions (> 2 bp) have been found in mutated immunoglobulin genes, our results, for the first time, firmly link these deletions/insertions to somatic hypermutations; their frequency was found to be 2.2% of the observed mutational events in the non-translated gene regions. HF-1 is the first follicular lymphoma line successfully established from a lymphoma known to have hypermutated its Ig genes during the malignant growth. It is a candidate cell line to be studied for its ability to generate mutations of B cell type in cell cultures.
取自一名滤泡性淋巴瘤患者的活检标本被分成两个片段。从其中一个片段中提取DNA，对功能性重链（IgH）基因的一个1.2 kb区域进行扩增、克隆和测序（8个克隆）。从另一个片段建立了一个细胞系（HF-1）。从该细胞系中扩增IgH基因区域，不进行克隆直接测序。获得的9个序列可以排列成一个谱系树，其中各个序列与推导的祖先序列相比有16 - 29个单核苷酸变化，有些还伴有插入和/或缺失。显然，这些序列改变是淋巴瘤生长过程中体细胞突变所致。将这些序列与已发表的两个人类JH区域（等位基因）种系序列进行比较，发现同源性约为20%。差异包括另外5个多核苷酸插入/缺失变化，其中最长的是一个101个核苷酸的插入。两个长插入与相邻的种系序列同源。我们认为观察到的大多数变化，包括长缺失和插入，代表或与Ig基因类型的体细胞超突变事件相关。虽然在少数情况下，在突变的免疫球蛋白基因中发现了大的缺失和插入（> 2 bp），但我们的结果首次将这些缺失/插入与体细胞超突变紧密联系起来；在非翻译基因区域中，发现它们的频率占观察到的突变事件的2.2%。HF-1是第一个从已知在恶性生长过程中其Ig基因发生超突变的淋巴瘤成功建立的滤泡性淋巴瘤细胞系。它是一个候选细胞系，可用于研究其在细胞培养中产生B细胞类型突变的能力。
