González Concepción, Guevara Paloma, Alarcón Inmaculada, Hernando Monserrat, Navajo José Alejandro, González-Buitrago José Manuel
Servicio de Bioquímica, Laboratorio de Autoinmunidad, Hospital Universitario, Salamanca, Spain.
Clin Biochem. 2002 Sep;35(6):463-9. doi: 10.1016/s0009-9120(02)00342-9.
Immunofluorescence assay (IFA) has been the standard method for antinuclear antibodies (ANA). To simplify and standardize the ANA test, generic ANA solid phase enzyme immunoassay has been promoted. The objective of the present work has been to study the relationship with IFA and the clinical usefulness of a generic EIA for ANA (COBAS Core HEp-2 ANA EIA, Roche Diagnostics).
We studied 74 healthy individuals, 119 patients with defined systemic autoimmune diseases, 26 patients with other autoimmune diseases, and 490 routine samples sent to laboratory for ANA analysis.
Precision study showed intra-assay coefficient of variations (CVs) below 8% and inter-assay CVs below 10%. In relation to IFA, a 0.6 kappa index of agreement was obtained. COBAS-ANA concentrations increased according to IFA titer and greatest COBAS-ANA responses were obtained with pure or mixed homogeneous patterns and centromeric patterns. Analysis of COBAS-ANA response to particular antigenic specificities showed that SS-B, Scl-70 and U1sn-RNP specificities were saturating at high concentrations, whereas Jo-1, SS-A and nuclear and centromeric specificities exhibited lower responses. Elevated serum concentrations of IgG and IgM did not interfere COBAS-ANA, but high serum rheumatoid factor (RF) concentrations produced a decrease of ANA. For systemic lupus erythematosus (SLE) patients, the COBAS-ANA best efficiency was obtained with a cut-off of 0.9, with a sensitivity of 97% and a specificity of 88%, whereas the best IFA-ANA efficiency was obtained with a 1:80 dilution, giving a sensitivity of 90% and a specificity of 99%. There were no differences between areas under ROC curves for COBAS-ANA and IFA-ANA. For other systemic and nonsystemic autoimmune diseases sensitivity and specificity of COBAS-ANA were similar or higher than that of 1:160 IFA-ANA titer.
Sensitivity and specificity of COBAS Core ANA-EIA for SLE and other systemic and nonsystemic autoimmune diseases, together with performance characteristics make it an adequate automated system for ANA screening.
免疫荧光法（IFA）一直是检测抗核抗体（ANA）的标准方法。为了简化和规范ANA检测，通用型ANA固相酶免疫测定法得到了推广。本研究的目的是探讨通用型酶免疫测定法（COBAS Core HEp-2 ANA EIA，罗氏诊断公司）与IFA的关系及其临床应用价值。
我们研究了74名健康个体、119名明确诊断为系统性自身免疫性疾病的患者、26名患有其他自身免疫性疾病的患者以及490份送往实验室进行ANA分析的常规样本。
精密度研究显示批内变异系数（CV）低于8%，批间CV低于10%。与IFA相比，一致性kappa指数为0.6。COBAS - ANA浓度随IFA滴度增加而升高，纯合或混合均匀型及着丝粒型的COBAS - ANA反应最强。对特定抗原特异性的COBAS - ANA反应分析表明，SS - B、Scl - 70和U1sn - RNP特异性在高浓度时达到饱和，而Jo - 1、SS - A以及核型和着丝粒型特异性反应较低。血清IgG和IgM浓度升高不影响COBAS - ANA，但血清类风湿因子（RF）浓度升高会导致ANA降低。对于系统性红斑狼疮（SLE）患者，COBAS - ANA的最佳效率在临界值为0.9时获得，敏感性为97%，特异性为88%，而IFA - ANA的最佳效率在1:80稀释时获得，敏感性为90%，特异性为99%。COBAS - ANA和IFA - ANA的ROC曲线下面积无差异。对于其他系统性和非系统性自身免疫性疾病，COBAS - ANA的敏感性和特异性与1:160 IFA - ANA滴度相似或更高。
COBAS Core ANA - EIA对SLE及其他系统性和非系统性自身免疫性疾病的敏感性和特异性，以及其性能特征使其成为一种适用于ANA筛查的自动化系统。
