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

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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.