Palinski W, Hörkkö S, Miller E, Steinbrecher U P, Powell H C, Curtiss L K, Witztum J L
Department of Medicine, University of California, San Diego 92093, USA.
J Clin Invest. 1996 Aug 1;98(3):800-14. doi: 10.1172/JCI118853.
Many reactive products may be formed when LDL undergoes lipid peroxidation, which in turn can react with lipids, apoproteins, and proteins, generating immunogenic neoepitopes. Autoantibodies recognizing model epitopes of oxidized low density lipoprotein, such as malondialdehydelysine, occur in plasma and in atherosclerotic lesions of humans and animals. Because apo E-deficient mice develop particularly high titers of such autoantibodies, we used their spleens to clone 13 monoclonal antibodies to various epitopes of oxidized LDL ("E0 antibodies"). Binding and competitive RIAs demonstrated significant differences in fine specificity even between E0 antibodies initially selected for binding to the same screening antigen. For example, some E0 antibodies selected for binding to malondialdehyde-LDL also recognized copper oxidized LDL, acrolein-LDL, or LDL modified by arachidonic or linoleic acid oxidation products. Circulating IgG and IgM autoantibodies binding to copper-oxidized LDL, 4-hydroxynonenal-LDL, acrolein-LDL, and LDL modified with arachidonic or linoleic acid oxidation products were found in apo E-deficient mice, suggesting that the respective antigens are formed in vivo. Epitopes recognized by some of the E0 monoclonal antibodies were also found on human circulating LDL. Each of the E0 monoclonal antibodies immunostained rabbit and human atherosclerotic lesions, and some of them yielded distinct staining patterns in advanced lesions. Together, this suggests that the natural monoclonal antibodies recognize different epitopes of complex structures formed during oxidation of lipoproteins, or epitopes formed independently at different lesion sites. Our data demonstrate that a profound immunological response to a large number of different epitopes of oxidized lipoproteins occurs in vivo. The availability of "natural" monoclonal autoantibodies should facilitate the identification of specific epitopes inducing this response.
当低密度脂蛋白（LDL）发生脂质过氧化时，可能会形成许多反应性产物，这些产物进而可与脂质、载脂蛋白和蛋白质发生反应，产生免疫原性新表位。识别氧化型低密度脂蛋白模型表位（如丙二醛赖氨酸）的自身抗体存在于人和动物的血浆及动脉粥样硬化病变中。由于载脂蛋白E缺乏的小鼠会产生特别高滴度的此类自身抗体，我们利用它们的脾脏克隆了13种针对氧化型LDL不同表位的单克隆抗体（“E0抗体”）。结合和竞争性放射免疫分析表明，即使是最初选择用于结合相同筛选抗原的E0抗体，其精细特异性也存在显著差异。例如，一些选择用于结合丙二醛-LDL的E0抗体也能识别铜氧化LDL、丙烯醛-LDL或经花生四烯酸或亚油酸氧化产物修饰的LDL。在载脂蛋白E缺乏的小鼠中发现了与铜氧化LDL、4-羟基壬烯醛-LDL、丙烯醛-LDL以及经花生四烯酸或亚油酸氧化产物修饰的LDL结合的循环IgG和IgM自身抗体，这表明相应的抗原是在体内形成的。一些E0单克隆抗体识别的表位也存在于人类循环LDL上。每种E0单克隆抗体都能对兔和人的动脉粥样硬化病变进行免疫染色，其中一些在晚期病变中产生了不同的染色模式。综上所述，这表明天然单克隆抗体识别脂蛋白氧化过程中形成的复杂结构的不同表位，或在不同病变部位独立形成的表位。我们的数据表明，体内对氧化脂蛋白的大量不同表位会发生深刻的免疫反应。“天然”单克隆自身抗体的可得性应有助于鉴定诱导这种反应的特定表位。
