SOS Laboratorio Immunologia e Allegologia Ospedale S. Giovanni di Dio Firenze, Florence, Italy.
Istituto Auxologico Italiano, IRCCS, Experimental Laboratory of Immunorheumatology, Cusano Milanino, Milan, Italy.
Clin Chem Lab Med. 2019 Oct 25;57(11):1764-1769. doi: 10.1515/cclm-2019-0454.
Background The dense fine speckled (DFS) is one of the most common patterns that can be observed as a result of the anti-nuclear antibodies (ANA) test on HEp-2 cells and is mostly caused by antibodies to DFS70 as the main antigenic target. As was recently demonstrated, isolated anti-DFS70 positivity can be used as an aid in the exclusion of ANA associated rheumatic diseases (AARD) due to the opportunity to better interpret unexplained positive IIF ANA results. Methods Our study included 333 subjects with AARD, 51 undifferentiated connective tissue disease (UCTD) patients, 235 disease controls and 149 healthy blood donors from an Italian cohort. All samples were tested for anti-DFS70 and anti-ENA antibodies using QUANTA Flash assays (Inova Diagnostics, San Diego, CA, USA). Results No differences in the prevalence of anti-DFS70 antibodies were seen among AARD, non-AARD and UCTD (2.1% [7/333] vs. 2.3% [9/384] vs. 5.9% [3/51], respectively; p-value = 0.188). AARD patients positive for anti-DFS70 antibodies showed in all cases an accompanying anti-ENA specificity. In contrast, monospecific anti-DFS70 antibodies showed a significantly different distribution with a clear trend across the main groups (AARD vs. non-AARD vs. UCTD: 0% [0/7] vs. 22% [2/9] vs. 100% [3/3], p = 0.007). Anti-DFS70 antibody levels among AARD, non-AARD and UCTD patients were not significantly different (p = 0.094). Within the anti-DFS70 antibody positive cases, AARD cohort showed a higher variability (median [min-max]: 3.2 [3.2-450.8] CU) compared to non-AARD (median [min-max]: 3.2 [3.2-75.7] CU) and UCTD patients (median [min-max]: 3.2 [3.2-59.0] CU). Conclusions Our preliminary data showed a similar frequency of anti-DFS70 antibodies in AARD, UCTD and non-AARD cohorts. Monospecificity of anti-DFS70 antibodies but not their mere presence is the key element in the diagnostic algorithm. Mono-specific anti-DFS70 antibodies might be a helpful biomarker to discriminate individuals with AARD from non-AARD presenting with a positive ANA.
致密细斑点（DFS）是抗核抗体（ANA）检测在 HEp-2 细胞上观察到的最常见模式之一，主要由针对 DFS70 的抗体作为主要抗原靶标引起。最近的研究表明，由于有机会更好地解释原因不明的阳性 IIF ANA 结果，孤立的抗 DFS70 阳性可作为排除与 ANA 相关的风湿性疾病（AARD）的辅助手段。
我们的研究包括来自意大利队列的 333 例 AARD 患者、51 例未分化结缔组织病（UCTD）患者、235 例疾病对照和 149 名健康献血者。使用 QUANTA Flash 检测试剂盒（Inova Diagnostics，圣地亚哥，CA，美国）检测所有样本的抗 DFS70 和抗 ENA 抗体。
AARD、非 AARD 和 UCTD 患者的抗 DFS70 抗体阳性率无差异（分别为 2.1%[7/333]、2.3%[9/384]和 5.9%[3/51]；p 值=0.188）。抗 DFS70 抗体阳性的 AARD 患者均伴有抗 ENA 特异性。相反，单特异性抗 DFS70 抗体的分布明显不同，在主要组中呈明显趋势（AARD 与非 AARD 与 UCTD：0%[0/7]与 22%[2/9]与 100%[3/3]；p=0.007）。AARD、非 AARD 和 UCTD 患者的抗 DFS70 抗体水平无显著差异（p=0.094）。在抗 DFS70 抗体阳性病例中，AARD 组的变异度较高（中位数[最小-最大]：3.2[3.2-450.8] CU），而非 AARD 组（中位数[最小-最大]：3.2[3.2-75.7] CU）和 UCTD 组（中位数[最小-最大]：3.2[3.2-59.0] CU）。
我们的初步数据显示，AARD、UCTD 和非 AARD 队列中抗 DFS70 抗体的频率相似。抗 DFS70 抗体的单特异性而不是其存在本身是诊断算法中的关键因素。单特异性抗 DFS70 抗体可能是区分具有阳性 ANA 的 AARD 和非 AARD 个体的有用生物标志物。
