Wang J, Dong X, Stojanov L, Kimpel D, Satoh M, Reeves W H
University of North Carolina at Chapel Hill, 27599-7280, USA.
Arthritis Rheum. 1997 Jul;40(7):1344-53. doi: 10.1002/1529-0131(199707)40:7<1344::AID-ART20>3.0.CO;2-V.
To examine humoral immune responses to the native Ku antigen and to evaluate the role of autoantibodies in stabilizing intermolecular contacts between the p70 and p80 Ku subunits.
Recombinant free human p70 and p80 Ku subunits and p70/p80 heterodimers were expressed in Sf9 (insect) cells using baculovirus vectors. Affinity-purified recombinant human p70, p80, and p70/p80 dimer were studied by enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation to evaluate autoantibody specificities in sera from 58 patients with systemic autoimmune disease.
Anti-Ku antibodies were detected by ELISA or immunoprecipitation using K562 cell Ku antigen. All of the sera were reactive with the native recombinant p70, p80, or p70/p80 antigens: 47% were anti-p70+,anti-p80+ and 32% were anti-p70-,anti-p80+, but only 3% were anti-p70+,anti-p80-. Unexpectedly, 18% of the sera recognized the p70/p80 dimer but did not recognize native p70 or p80 alone. A subset of sera containing autoantibodies that prevent the dissociation of p70 from p80 by high salt and detergent treatment was identified; monoclonal antibody (MAb) 162, a murine anti-Ku MAb, displays the same property. Autoantibodies that stabilize the p70-p80 interaction were found most frequently in sera containing both anti-p70 and anti-p80 antibodies.
Autoantibodies to the native p80 subunit of Ku are more common than are anti-p70 antibodies. When anti-p70 antibodies were detected, they generally were found together with anti-p80. A novel type of autoantibody capable of stabilizing the p70/p80 heterodimer was identified in human sera for the first time. These "stabilizing" autoantibodies are found in sera containing both anti-p70 and anti-p80 antibodies, and also are produced by mice immunized with human Ku antigen. Autoimmunity to Ku may be initiated with an immune response to p80, followed by spreading to p70. We hypothesize that stabilizing antibodies could facilitate the spreading of autoimmunity from one subunit of Ku to another by altering the processing of p70 or p80 by antigen-presenting cells.
检测对天然Ku抗原的体液免疫反应，并评估自身抗体在稳定p70和p80 Ku亚基之间分子间接触中的作用。
使用杆状病毒载体在Sf9（昆虫）细胞中表达重组游离人p70和p80 Ku亚基以及p70/p80异二聚体。通过酶联免疫吸附测定（ELISA）和免疫沉淀研究亲和纯化的重组人p70、p80和p70/p80二聚体，以评估58例系统性自身免疫病患者血清中的自身抗体特异性。
使用K562细胞Ku抗原通过ELISA或免疫沉淀检测到抗Ku抗体。所有血清均与天然重组p70、p80或p70/p80抗原发生反应：47%为抗p70阳性、抗p80阳性，32%为抗p70阴性、抗p80阳性，但只有3%为抗p70阳性、抗p80阴性。出乎意料的是，18%的血清识别p70/p80二聚体，但不单独识别天然p70或p80。鉴定出一部分含有自身抗体的血清，这些自身抗体可通过高盐和去污剂处理防止p70与p80解离；鼠抗Ku单克隆抗体（MAb）162具有相同特性。稳定p70-p80相互作用的自身抗体最常见于同时含有抗p70和抗p80抗体的血清中。
针对Ku天然p80亚基的自身抗体比抗p70抗体更常见。当检测到抗p70抗体时，它们通常与抗p80一起被发现。首次在人血清中鉴定出一种能够稳定p70/p80异二聚体的新型自身抗体。这些“稳定”自身抗体存在于同时含有抗p70和抗p80抗体的血清中，也由用人Ku抗原免疫的小鼠产生。对Ku的自身免疫可能始于对p80的免疫反应，随后扩散至p70。我们推测，稳定抗体可能通过改变抗原呈递细胞对p70或p80的加工处理，促进自身免疫从Ku的一个亚基扩散至另一个亚基。
