National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland.
Department of Gerontology and Public Health, National Institute of Geriatrics, Rheumatology and Rehabilitation, Warsaw, Poland.
Rheumatol Int. 2021 Mar;41(3):643-649. doi: 10.1007/s00296-020-04782-3. Epub 2021 Jan 26.
Primary Sjögren's syndrome (pSS) is an autoimmune disease with autoantibodies overproduction, including rheumatoid factors (RF). RF-IgA, IgG immunoglobulin classes are suggested as potential biomarkers of pSS. We studied 76 patients with pSS (ACR/Eular 2017); laboratory tests included ESR, C-reactive protein, concentrations of gamma globulins, RF, Anti-SS-A/Ro, and anti-SS-B/La. Eye dryness and keratoconjunctivitis sicca were confirmed with Schirmer's test, the ocular staining score (OSS) using lissamine green, fluorescein staining and biopsy of minor salivary gland with the histopathological evaluation. Differences between groups were analyzed with U Mann-Whitney test. Correlations between quantitative variables were assessed with the Spearman correlation coefficient.. The best diagnostic values of immunoglobulin concentration for discriminating pSS patients and healthy individuals are for RF-IgA. With cut-off of 21.5 EU/mL, the sensitivity is 72% and specificity is 100%. Very high specificity (100%) is also obtained for RF-IgM concentration of 74.1 EU/mL. Sensitivity is, however, smaller than that for RF-IgA and amounted to 61%. The RF-IgG is the poorest indicator of pSS with 51% of sensitivity and 95% of specificity. To summarize RF-IgA strongly associate with anti-SS-A and anti-SS-B autoantibodies. Both RF-IgA and RF-IgM may be used as diagnostic tools for pSS. Conclusions: among the three studied rheumatoid factor subtypes, RF-IgA showed the best diagnostic accuracy for pSS. RF-IgA correlated with anti-SS-A/Ro and anti-SS-B antibodies even more closely than RF-IgM. The assessment of the RF-IgA serum concentration may be helpful in the process of establishing pSS diagnosis.
原发性干燥综合征（pSS）是一种自身免疫性疾病，会导致自身抗体过度产生，包括类风湿因子（RF）。RF-IgA、IgG 免疫球蛋白类别被认为是 pSS 的潜在生物标志物。我们研究了 76 名 pSS 患者（ACR/Eular 2017）；实验室检查包括 ESR、C 反应蛋白、γ球蛋白浓度、RF、抗 SS-A/Ro 和抗 SS-B/La。使用 Schirmer 试验确认眼睛干燥和干燥性角结膜炎，使用 Lissamine 绿、荧光素染色和眼表染色评分（OSS）以及小唾液腺活检进行眼表染色评分（OSS），并进行组织病理学评估。使用 U 曼-惠特尼检验分析组间差异。用 Spearman 相关系数评估定量变量之间的相关性。用于区分 pSS 患者和健康个体的免疫球蛋白浓度的最佳诊断值为 RF-IgA。当截断值为 21.5 EU/mL 时，灵敏度为 72%，特异性为 100%。RF-IgM 浓度为 74.1 EU/mL 时，特异性也非常高（100%）。然而，RF-IgG 是 pSS 的最差指标，灵敏度为 51%，特异性为 95%。总结来说，RF-IgA 与抗 SS-A 和抗 SS-B 自身抗体强烈相关。RF-IgA 和 RF-IgM 均可作为 pSS 的诊断工具。结论：在三种研究的类风湿因子亚型中，RF-IgA 对 pSS 的诊断准确性最高。RF-IgA 与抗 SS-A/Ro 和抗 SS-B 抗体的相关性甚至比 RF-IgM 更密切。评估 RF-IgA 血清浓度可能有助于建立 pSS 诊断。
