Molecular biological study＼ies in a novel peripheral nerve myelin protein and its application to clinical neurology

我们试图描述一个恶性淋巴瘤和周围神经病变患者的血清IgG识别的35 kd抗原。在Western印迹上，血清IgG与人、牛和小鼠外周神经（PN）中的35-kd抗原反应，但不与其他神经和非神经组织反应。免疫组化显示PN的致密髓鞘中IgG呈免疫反应性。我们构建了人坐骨神经cDNA文库，并使用患者的IgG进行筛选。我们发现了三个独立的克隆体。对这些克隆的插入片段进行同源性搜索，发现这些插入片段与P0 cDNA同源。然而，所有插入片段均对应于P0 cDNA的3 '非翻译区。然后，为了生物化学分析35-kd抗原，制备人和牛坐骨神经的髓鞘组分。使用SDS-聚丙烯酰胺凝胶电泳，35 kd的抗原纯化的粗髓鞘馏分。当将35-kd抗原对患者IgG和单克隆抗P0抗体的免疫反应性与蛋白质P0对这些抗体的免疫反应性进行比较时，35-kd抗原与这两种抗体反应，但P0仅与单克隆抗P0抗体反应。这些结果表明35 kd抗原是P0的同种型的可能性。然而，这些自身抗体对35-kd抗原的存在似乎没有什么病理意义，因为循环自身抗体对抗原也被发现在恶性淋巴瘤患者的血清中没有相关的周围神经病变。

We tried to characterize a 35-kd antigen recognized by the serum IgG of a patient with malignant lymphoma and peripheral neuropathy. On western blotting, the serum IgG reacted with a 35-kd antigen in human, bovine and mouse peripheral nerves (PN) but not with other neural and non-neural tissues. Immunohistochemical analysis showed immunoreactivity for the IgG in the compact myelin of PN. We constructed a human sciatic nerve cDNA library and screened it using the patient's IgG. We identified three independent clones. A homology search of the inserts of these clones revealed that the inserts were homologous to P0 cDNA. However, all the inserts corresponded to the 3'-untranslational region of P0 cDNA. Then, to analyze the 35-kd antigen biochmically, myelin fractions of human and bovine sciatic nerve were prepared. Using SDS-polyacrylamide gel electrophresis, the 35-kd antigen was purified from the crude myelin fraction. When the immunoreactivities of the 35-kd antigen for the patient's IgG and monoclonal anti-P0 antibody were compared with those of protein P0 for these antibodies, the 35-kd antigen reacted with both the antibodies, but P0 reacted with only monoclonal anti-P0 antibody. These results indicate the possibility of the 35-kd antigen being an isoform of P0. However, the presence of these autoantibodies against the 35-kd antigen seems to be of little pathological significance, because circulating autoantibodies against the antigen were also found in the sera of patients with malignant lymphoma without associated peripheral neuropathy.