AUTHOR=Dai Yingxin , Li Enling , Chen Dandan , Niu Xiangyu , Wang Zhiqing , Lu Liangjing , Zheng Bing 

TITLE=Anti-DFS70 antibodies in systemic lupus erythematosus: Prevalence in a large Chinese cohort and an unexpected association with anti-dsDNA antibodies by a long-term follow-up

JOURNAL=Frontiers in Immunology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.913714

DOI=10.3389/fimmu.2022.913714

ISSN=1664-3224

ABSTRACT=Objective: Monospecific autoantibodies to dense fine speckles 70 (DFS70) antigen are purported to aid to exclude systemic autoimmune rheumatic diseases (SARD) such as systemic lupus erythematosus (SLE). However, the non-isolated anti-DFS70 still has a certain prevalence in SLE patients and the clinical significance remains unclear. We aimed to investigate the prevalence, clinical relevance, and value of long-term monitoring of anti-DFS70 antibodies in SLE patients. 
Methods: Anti-DFS70 antibodies were measured by enzyme-linked immunosorbent assay (ELISA) in 851 SLE patients, 211 healthy individuals and 194 patients with other SARD (except SLE). Demographic, serological, and clinical associations of anti-DFS70 antibodies were analyzed by a stepwise multivariable logistic regression model. Correlation of anti-DFS70 with anti-dsDNA, anti-C1q and SLE Disease Activity Index 2000 (SLEDAI-2K) was analyzed. 61 SLE patients with follow-up time ranging from 2 to 57 months were confirmed anti-DFS70 reactivity using both ELISA and line immunoassay. The dynamic variations of anti-DFS70 antibodies were evaluated with anti-dsDNA, anti-C1q and SLEDAI-2K during the follow-up. 
Results: Prevalence of anti-DFS70 was significantly higher in SLE (20.7% [176/851]) than healthy individuals (9.5% [20/211], P=0.0002) and other SARD (10.8% [21/194], P=0.002). Multivariable analysis revealed anti-DFS70-positive SLE patients were associated with younger age (odds ratio [OR] 0.982; 95% confidence interval [CI] 0.969, 0.995), higher frequency of anti-dsDNA (OR 1.598; 95%CI 1.107, 2.306) and anti-PCNA (OR 6.101; 95%CI 2.534, 14.688), higher levels of serum IgG (OR 1.097; 95%CI 1.067, 1.129) and were more likely to accompanied by mucosal ulcers (OR 5.921; 95%CI 1.652, 21.215). The O.D. value of anti-DFS70 positively correlated with levels of anti-dsDNA (r=0.183, P<0.0001) and anti-C1q (r=0.181, P<0.0001) respectively, but not with SLEDAI-2K (P=0.920). During the follow-up, 49 patients remained stable anti-DFS70 levels (42 negative and 7 positive). The other 12 patients experienced significant changes of anti-DFS70, and 83.3% (10/12) of them showed similar trends between anti-DFS70 and anti-dsDNA by evaluation of dynamic variations. 
Conclusion: Anti-DFS70 antibodies seem to be prevalent in Chinese SLE patients. Positive association of anti-DFS70 with anti-dsDNA and consistent dynamic variation between anti-DFS70 and anti-dsDNA during the follow-up suggested a potential relationship between anti-DFS70 and anti-dsDNA in patients with SLE.