Muryoi T, Kasturi K N, Kafina M J, Cram D S, Harrison L C, Sasaki T, Bona C A
Department of Microbiology, Mount Siani School of Medicine, New York, New York 10029-6574.
J Exp Med. 1992 Apr 1;175(4):1103-9. doi: 10.1084/jem.175.4.1103.
We have generated for the first time monoclonal antibodies (mAbs) specific for topoisomerase I (topo I) from scleroderma patients, and tight skin mice which develop a scleroderma-like syndrome. The epitope specificity of these antibodies has been determined using a series of fusion proteins containing contiguous portions of topo I polypeptide. Western blot analysis demonstrated that both human and mouse mAbs bound strongly to fusion protein C encompassing the NH2-terminal portion of the enzyme, and weakly to fusion proteins F and G containing regions close to the COOH-terminal end of the molecule. This crossreactivity is related to a tripeptide sequence homology in F, G, and C fusion proteins. It is interesting that a pentapeptide sequence homologous to that in fusion protein C was identified in the UL70 protein of cytomegalovirus, suggesting that activation of autoreactive B cell clones by molecular mimicry is possible. Both human and mouse mAbs exhibiting the same antigen specificity, also share an interspecies cross-reactive idiotope. These data suggest that B cell clones producing antitopo autoantibodies present in human and mouse repertoire are conserved during phylogeny, and are activated during the development of scleroderma disease.
我们首次从硬皮病患者以及患有类似硬皮病综合征的紧皮小鼠中产生了针对拓扑异构酶I（topo I）的单克隆抗体（mAbs）。使用一系列包含topo I多肽连续部分的融合蛋白确定了这些抗体的表位特异性。蛋白质印迹分析表明，人和小鼠的mAbs都与包含该酶NH2末端部分的融合蛋白C强烈结合，而与包含靠近分子COOH末端区域的融合蛋白F和G弱结合。这种交叉反应性与F、G和C融合蛋白中的三肽序列同源性有关。有趣的是，在巨细胞病毒的UL70蛋白中鉴定出了与融合蛋白C中的五肽序列同源的序列，这表明通过分子模拟激活自身反应性B细胞克隆是可能的。表现出相同抗原特异性的人和小鼠mAbs也共享种间交叉反应性独特型。这些数据表明，在人类和小鼠库中产生抗拓扑异构酶自身抗体的B细胞克隆在系统发育过程中是保守的，并在硬皮病疾病发展过程中被激活。
