Mapping of myeloperoxidase epitopes recognized by MPO-ANCA using human-mouse MPO chimers
Mapping of myeloperoxidase epitopes recognized by MPO-ANCA using human-mouse MPO chimers
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DOI：
10.1038/sj.ki.5000354
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发表时间：
2006-05-01
影响因子：
19.6
通讯作者：
Nachman, P. H.
中科院分区：
文献类型：
--
作者：
Erdbrugger, U.;Hellmark, T.;Nachman, P. H.
髓过氧化物酶（MPO）是小血管炎和少免疫性坏死性肾小球肾炎患者抗神经细胞胞质自身抗体（ANCA）的主要靶抗原之一。迄今为止，MPO-ANCA的靶表位仍然不清楚。人MPO-ANCA通常不结合小鼠MPO。我们利用人和小鼠MPO之间的差异来鉴定MPO-ANCA的靶区域。我们产生了五个嵌合MPO分子，其中我们用来自其他物种的同源对应物替换了人类或小鼠分子的不同片段。在本研究筛选的28名患者的血清样本中，对来自14名MPO-ANCA相关血管炎患者的43份样本进行了重组人和小鼠MPO以及嵌合分子组的检测。64%和71%的患者血清分别在氨基酸517-667或668-745区域与重链羧基末端结合。没有患者血清结合MPO轻链或重链的氨基末端。所有血清仅结合MPO的一个或两个区域。虽然10例患者中有6例的MPO-ANCA结合模式随时间（4-27个月）而改变，但这种变化并不常见。由于MPO的天然形式和重组形式之间的构象差异，可能未检测到MPO-ANCA的其他靶区域。MPO-ANCA不靶向单个表位，而是靶向MPO的少数区域，主要在重链的羧基末端。
Myeloperoxidase ( MPO) is one of the major target antigens of antineutrophil cytoplasmic autoantibodies ( ANCA) found in patients with small-vessel vasculitis and pauci-immune necrotizing glomerulonephritis. To date, the target epitopes of MPO-ANCA remain poorly defined. Human MPO-ANCA do not typically bind mouse MPO. We utilized the differences between human and mouse MPO to identify the target regions of MPO-ANCA. We generated five chimeric MPO molecules in which we replaced different segments of the human or mouse molecules with their homologous counterpart from the other species. Of serum samples from 28 patients screened for this study, 43 samples from 14 patients with MPO-ANCA-associated vasculitis were tested against recombinant human and mouse MPO and the panel of chimeric molecules. Sera from 64 and 71% of patients bound to the carboxy-terminus of the heavy chain, in the regions of amino acids 517-667 or 668-745, respectively. No patient serum bound the MPO light chain or the amino-terminus of the heavy chain. All sera bound to only one or two regions of MPO. Although the pattern of MPO-ANCA binding changed over time ( 4-27 months) in 6 of 10 patients with several serum samples, such changes were infrequent. Other target regions of MPO-ANCA may not have been detected due to conformational differences between the native and recombinant forms of MPO. MPO-ANCA do not target a single epitope, but rather a small number of regions of MPO, primarily in the carboxy-terminus of the heavy chain.