Stanford University School of Medicine, Department of Dermatology, Stanford, CA, USA.
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, MD, USA.
Clin Exp Rheumatol. 2019 Nov-Dec;37(6):1048-1051. Epub 2019 Jul 19.
To compare autoantibody-defined dermatomyositis sub-populations using immunoprecipitation-based assays, a commercially available line immunoblot assay and alternate commercial ELISA assays.
Banked plasma from 261 carefully phenotyped dermatomyositis patients was studied. Immunoprecipitation-based assays were used to detect antibodies against Mi2, TIF1-γ MDA5, NXP2, SAE1 and PM-Scl, while anti-Jo1 antibodies were assayed using ELISA. These data were compared with that obtained using a commercial line immunoblot, and, additionally, for Mi2, TIF1-γ, MDA5, commercially available ELISA kits. Test agreement was measured using Cohen's kappa statistic, and phenotypic differences between differentially identified groups are described.
Line immunoblot, immunoprecipitation, and ELISA detected increasingly larger nested pools of anti-TIF1-γ samples, with increasing frequency of concurrent anti-Mi2 reactivity and decreasing incidence of malignancy. Line immunoblot and immunoprecipitation showed fair concordance for identifying anti-NXP2 antibodies (Cohen's kappa=0.71) but very good agreement for identifying antibodies against Mi2, MDA5, and SAE1 (Cohen's κ=0.9, 0.94, 0.88, respectively). Anti-PM-Scl results showed moderate agreement (Cohen's κ=0.48) between immunoblot and immunoprecipitation.
Our results demonstrate that for some specificities, especially anti-TIF1-γ, antibody results obtained using different assay platforms vary, and identify significantly different patient populations. These findings highlight the need for standard adoption of carefully validated platforms to detect dermatomyositis autoantibodies.
通过基于免疫沉淀的检测、商业上可用的线免疫印迹检测以及替代的商业 ELISA 检测来比较自身抗体定义的皮肌炎亚群。
研究了 261 例精心表型的皮肌炎患者的银行血浆。基于免疫沉淀的检测用于检测针对 Mi2、TIF1-γ MDA5、NXP2、SAE1 和 PM-Scl 的抗体，而抗 Jo1 抗体则使用 ELISA 进行检测。将这些数据与商业线免疫印迹以及 Mi2、TIF1-γ、MDA5 的商业 ELISA 试剂盒获得的数据进行比较。使用 Cohen's kappa 统计测量测试一致性，并描述不同鉴定组之间的表型差异。
线免疫印迹、免疫沉淀和 ELISA 检测到针对抗 TIF1-γ 的嵌套样本越来越多，同时存在抗 Mi2 反应的频率增加，恶性肿瘤的发生率降低。线免疫印迹和免疫沉淀在识别抗 NXP2 抗体方面显示出良好的一致性（Cohen's kappa=0.71），但在识别 Mi2、MDA5 和 SAE1 抗体方面具有非常好的一致性（Cohen's κ=0.9、0.94、0.88）。免疫印迹和免疫沉淀在识别抗 PM-Scl 方面显示出中度一致性（Cohen's κ=0.48）。
我们的结果表明，对于某些特异性，尤其是抗 TIF1-γ，使用不同检测平台获得的抗体结果存在差异，并确定了明显不同的患者群体。这些发现强调了需要采用经过精心验证的平台来标准化检测皮肌炎自身抗体。
