Marx A, O'Connor R, Tzartos S, Kalies I, Kirchner T, Müller-Hermelink H K
Pathologisches Institut, Universität Würzburg, FRG.
Thymus. 1989;14(1-3):171-8.
Immunohistochemical studies have shown that almost all thymomas of myasthenia gravis (MG) patients contain proteins which share antigenic determinants with the nicotinic acetylcholine receptor (AChR) of human muscle. Here we describe one of the proteins (p153) which (1) is not part of a compound structure, (2) has a MW of 153 kd, (3) has an isoelectric point of 5.0, and (4) is probably free of sugar residues. The protein does not bind mAb to the main immunogenic region of the AChR and has no alpha-bungarotoxin (alpha-btx) binding site. p153 was not found in both normal tissues and a variety of tumours. However, the epitope defined by mAb155 also occurs in at least two other proteins (from muscle and TE671 cells) which have MW different from 153 kd and which are unrelated to AChR. Experiments presented elsewhere [Geuder et al., this volume] show that there are no proteins in thymomas which share an extensive molecular homology with the AChR. All these findings suggest that p153 is unrelated to the AChR. As p153 is the only protein demonstrated in thymomas which is significantly correlated with MG and which shares an antigenic determinant with AChR, p153 is a candidate protein determining the AChR-specificity of the autoimmune process in MG.
免疫组织化学研究表明，几乎所有重症肌无力（MG）患者的胸腺瘤都含有与人类肌肉烟碱型乙酰胆碱受体（AChR）具有共同抗原决定簇的蛋白质。在此，我们描述其中一种蛋白质（p153），它（1）不是复合结构的一部分，（2）分子量为153kd，（3）等电点为5.0，且（4）可能不含糖基。该蛋白质不与针对AChR主要免疫原性区域的单克隆抗体结合，也没有α-银环蛇毒素（α-btx）结合位点。在正常组织和多种肿瘤中均未发现p153。然而，单克隆抗体155所定义的表位也存在于至少另外两种蛋白质（来自肌肉和TE671细胞）中，它们的分子量与153kd不同且与AChR无关。其他地方展示的实验[Geuder等人，本卷]表明，胸腺瘤中不存在与AChR具有广泛分子同源性的蛋白质。所有这些发现表明p153与AChR无关。由于p153是在胸腺瘤中唯一被证实与MG显著相关且与AChR具有共同抗原决定簇的蛋白质，因此p153是决定MG自身免疫过程中AChR特异性的候选蛋白质。
