Mironova M, Virella G, Lopes-Virella M F
Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, USA.
Arterioscler Thromb Vasc Biol. 1996 Feb;16(2):222-9. doi: 10.1161/01.atv.16.2.222.
Autoantibodies to oxidized LDL have been reported in normal subjects and in patients with arteriosclerosis, but their possible pathogenic role is not yet well defined. One important problem is the existence of contradictory data reported by different groups concerning the associations between antioxidized LDL autoantibodies and the presence or progression of arteriosclerotic lesions. Such contradictions led us to decide to isolate and characterize antioxidized LDL antibodies by affinity chromatography with the use of oxidized LDL cross-linked to Sepharose. Antioxidized LDL antibodies were isolated from selected serum samples obtained from eight subjects. Seven of them (six patients and one control subject) had high levels of antioxidized LDL antibody during screening. The other subject, a healthy volunteer, had a low level of antibody. All purified antibodies contained IgG (of subclasses 1 and 3) as the predominant isotype and were primarily specific for oxidized LDL but showed some cross-reactivity with malondialdehyde-modified LDL and native LDL. Two of the purified antibodies cross-reacted with cardiolipin. We determined average dissociation constants for the antioxidized LDL antibodies purified from five individuals, which varied between 2.4 x 10(-7) and 7.5 x 10(-7) mol/L, whereas the average dissociation constant of rabbit hyperimmune anti-LDL antibody was determined to be 2.7 x 10(-8) mol/L. In conclusion, we have purified human autoantibodies reactive with oxidized LDL that appear to be predominantly of moderate-to-low affinity and of variable cross-reactivity. The predominance of IgG1 and IgG3 antibodies is significant from the standpoint of potential pathogenicity, since these two subclasses activate the classic complement pathway system and have the highest binding affinities for Fc gamma receptors on phagocytic cells.
在正常受试者和动脉粥样硬化患者中均已报道存在氧化型低密度脂蛋白自身抗体，但其可能的致病作用尚未明确界定。一个重要问题是不同研究小组报告的数据相互矛盾，这些数据涉及抗氧化型低密度脂蛋白自身抗体与动脉粥样硬化病变的存在或进展之间的关联。这些矛盾促使我们决定使用与琼脂糖交联的氧化型低密度脂蛋白通过亲和层析法分离并鉴定抗氧化型低密度脂蛋白抗体。从八名受试者的选定血清样本中分离出了抗氧化型低密度脂蛋白抗体。其中七名（六名患者和一名对照受试者）在筛查期间抗氧化型低密度脂蛋白抗体水平较高。另一名受试者是健康志愿者，其抗体水平较低。所有纯化的抗体均以IgG（1和3亚类）作为主要的同种型，主要对氧化型低密度脂蛋白具有特异性，但与丙二醛修饰的低密度脂蛋白和天然低密度脂蛋白存在一些交叉反应。两种纯化的抗体与心磷脂发生交叉反应。我们测定了从五名个体纯化的抗氧化型低密度脂蛋白抗体的平均解离常数，其范围在2.4×10⁻⁷至7.5×10⁻⁷mol/L之间，而兔超免疫抗低密度脂蛋白抗体的平均解离常数测定为2.7×10⁻⁸mol/L。总之，我们纯化了与氧化型低密度脂蛋白反应的人自身抗体，这些抗体似乎主要具有中低亲和力且交叉反应性各异。从潜在致病性的角度来看，IgG1和IgG3抗体的优势很明显，因为这两个亚类可激活经典补体途径系统，并且对吞噬细胞上的Fcγ受体具有最高的结合亲和力。
