Study in cDNA Cloning of Peripheral Myelin-Specific Antigen Associated with Autoimmune Peripheral Neuritis.

我们在恶性淋巴瘤患者的血清中发现了抗外周髓磷脂的循环自身抗体。免疫印迹和免疫组化结果显示，血清与髓鞘36kd抗原呈阳性反应。血清与中枢神经系统和其他内脏器官无反应。这些数据表明，该抗原可能是一种新的外周髓鞘成分。本研究建立了人周围神经λ表达文库，并从人坐骨神经中提取poly（A）^+RNA，合成双链cDNA，将其连接到λ gt11表达载体上，获得了编码该抗原的cDNA克隆。用来自患者的血清对该cDNA文库进行免疫筛选导致cDNA克隆的分离。将其亚克隆到pGEX质粒载体中，用染料双脱氧终止法测定其核苷酸序列，序列分析结果表明，该cDNA克隆含有一个880 bp的插入片段，其中没有终止密码子，推测该cDNA片段可能是开放阅读框架的一部分。用该核苷酸序列和预测的氨基酸序列在GenBank和Swissprot数据库中进行同源性检索，发现与数据库中已知的序列没有同源性。在许多自身免疫性周围神经炎的病例中，已报道了周围神经系统中针对各种抗原的循环自身抗体。在这项研究中，一名患者的尸检显示周围神经有密集的细胞浸润。提示髓鞘抗原在自身免疫性神经炎的发病机制中可能起重要作用。

We found circulating autoantibodies against peripheral myelin, in sera from the patients with malignant lymphoma. Immunoblots and immunohistochemical technique showed that the sera reacted with 36kd antigen of peripheral myelin. The sera did not react with the central nervous system and other visceral organs at all. These data suggested that the antigen might be a novel component of peripheral myelin. In this study, we established a lambda expression library of human peripheral nerve, and isolated a cDNA clone encoding the antigen.We synthesized double-stranded cDNA from poly (A) ^+RNA extracted from human sciatic nerve, and ligated this cDNA to lambda gt11 expression vector. Immunoscreening of this cDNA library by sera from the patients resulted in isolation of a cDNA clone. The isolated cDNA was subcloned into pGEX plasmid vector and nucleotide sequences of the cDNA were obtained by dye-dideoxy termination method.The results of sequence analysis showed that the cDNA clone had an insert of 880bps, in which there was no termination codon, suggesting that the cDNA fragment might be a part of open reading frame. The nucleotide sequences and predicted amino acid sequences were used in a homology search of GenBank and Swissprot data bases and revealed no homology with known sequences uploaded in the data bases up to now.In many cases of autoimmune peripheral neuritis, circulating autoantibodies against various antigens in the peripheral nervous systems have been reported. In this study, a postmortem examination of one patient showed intensive cellular infiltration into peripheral nerves. This finding suggests that the isolated myelin antigen may play an important role in pathogenetic mechanisms of autoimmune neuritis.