Zhang Bingxin, Zheng Rui, Wang Jing, Bu Dingfang, Zhu Xuejun
Department of Dermatology, Peking University First Hospital, Beijing, China.
J Invest Dermatol. 2006 Apr;126(4):832-40. doi: 10.1038/sj.jid.5700198.
Sera from paraneoplastic pemphigus (PNP) immunoprecipitate multiple antigens from human epidermal protein extract. In this study, we further characterized the autoantibodies in 12 PNP sera. Immunoblotting using recombinant linker subdomains of envoplakin, periplakin, desmoplakin, and bullous pemphigoid antigen I found that 11 of the 12 sera recognized linker subdomains of envoplakin and periplakin. We then synthesized 12 peptides covering the linker subdomain of envoplakin for ELISA. One of the peptides, peptide no. 8, was recognized by nine out of the 12 sera with a higher affinity. A method of ligand-receptor binding assay was designed and performed using this peptide labeled with fluorescence as the ligand. Peptide no. 8 bound to CD20+ cells in Castleman's tumors from the patients whose sera were positive to this peptide by ELISA. Our data suggest that the linker subdomain of plakin proteins may be one of the major areas recognized by PNP autoantibodies, and epitopes in the linker subdomain of envoplakin recognized by PNP autoantibodies with a high affinity are dispersed in several areas and are variable among PNP patients. We also demonstrate that B-lymphocyte clones specifically reacting to epidermal proteins exist in Castleman's tumors from PNP.
副肿瘤性天疱疮（PNP）患者的血清可从人表皮蛋白提取物中免疫沉淀多种抗原。在本研究中，我们进一步对12份PNP血清中的自身抗体进行了特性分析。使用重组的内斑蛋白、周斑蛋白、桥粒斑蛋白和大疱性类天疱疮抗原I的连接子结构域进行免疫印迹分析，发现12份血清中有11份识别内斑蛋白和周斑蛋白的连接子结构域。然后，我们合成了覆盖内斑蛋白连接子结构域的12种肽段用于酶联免疫吸附测定（ELISA）。其中一种肽段，即8号肽段，被12份血清中的9份以较高亲和力识别。设计并进行了一种配体-受体结合测定方法，使用这种标记有荧光的肽段作为配体。8号肽段与ELISA检测中血清对该肽段呈阳性反应的患者的Castleman病肿瘤中的CD20+细胞结合。我们的数据表明，斑蛋白的连接子结构域可能是PNP自身抗体识别的主要区域之一，PNP自身抗体以高亲和力识别的内斑蛋白连接子结构域中的表位分散在几个区域，且在PNP患者中存在差异。我们还证明，PNP患者的Castleman病肿瘤中存在对表皮蛋白有特异性反应的B淋巴细胞克隆。
