Sanchez-Hernandez Evelyn S, Ortiz-Hernandez Greisha L, Ochoa Pedro T, Reeves Michael, Bizzaro Nicola, Andrade Luis E C, Mahler Michael, Casiano Carlos A
Center for Health Disparities and Molecular Medicine, Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA 92350, USA.
Laboratorio di Patologia Clinica, Ospedale San Antonio, Azienda Sanitaria Universitaria Integrata, 33100 Udine, Italy.
Diagnostics (Basel). 2023 Jan 7;13(2):222. doi: 10.3390/diagnostics13020222.
The monospecific dense fine speckled (DFS) immunofluorescence assay (IFA) pattern is considered a potential marker to aid in exclusion of antinuclear antibody (ANA)-associated rheumatic diseases (AARD). This pattern is typically produced by autoantibodies against transcription co-activator DFS70/LEDGFp75, which are frequently found in healthy individuals and patients with miscellaneous inflammatory conditions. In AARD patients, these antibodies usually co-exist with disease-associated ANAs. Previous studies reported the occurrence of monospecific autoantibodies that generate a DFS-like or pseudo-DFS IFA pattern but do not react with DFS70/LEDGFp75. We characterized this pattern using confocal microscopy and immunoblotting. The target antigen associated with this pattern partially co-localized with DFS70/LEDGFp75 and its interacting partners H3K36me2, an active chromatin marker, and MLL, a transcription factor, in HEp-2 cells, suggesting a role in transcription. Immunoblotting did not reveal a common protein band immunoreactive with antibodies producing the pseudo-DFS pattern, suggesting they may recognize diverse proteins or conformational epitopes. Given the subjectivity of the HEp-2 IFA test, the awareness of pseudo-DFS autoantibodies reinforces recommendations for confirmatory testing when reporting patient antibodies producing a putative DFS pattern in a clinical setting. Future studies should focus on defining the potential diagnostic utility of the pseudo-DFS pattern and its associated antigen(s).
单特异性致密细斑点（DFS）免疫荧光测定（IFA）模式被认为是有助于排除抗核抗体（ANA）相关风湿性疾病（AARD）的潜在标志物。这种模式通常由针对转录共激活因子DFS70/LEDGFp75的自身抗体产生，这些自身抗体在健康个体和患有各种炎症性疾病的患者中经常出现。在AARD患者中，这些抗体通常与疾病相关的ANA共存。先前的研究报道了产生DFS样或假DFS IFA模式但不与DFS70/LEDGFp75反应的单特异性自身抗体的出现。我们使用共聚焦显微镜和免疫印迹对这种模式进行了表征。与这种模式相关的靶抗原在HEp-2细胞中与DFS70/LEDGFp75及其相互作用伙伴H3K36me2（一种活性染色质标记物）和MLL（一种转录因子）部分共定位，提示其在转录中起作用。免疫印迹未显示与产生假DFS模式的抗体发生免疫反应的共同蛋白条带，表明它们可能识别多种蛋白质或构象表位。鉴于HEp-2 IFA检测的主观性，在临床环境中报告产生假定DFS模式的患者抗体时，对假DFS自身抗体的认识强化了进行确证检测的建议。未来的研究应侧重于确定假DFS模式及其相关抗原的潜在诊断效用。
