The Prevalence of Anti-DFS70 Antibodies in SLE and Non-SLE Patients

Background: The presence of anti-DFS70 antibodies was considered by some rheumatologists as a tool to help exclude the diagnosis of systemic autoimmune rheumatic diseases (SARDs) such as systemic lupus erythematosus (SLE). However, several studies reported the controversial result. The golden standard for anti-DFS70 antibody detection is indirect immunofluorescence (IIF) assay. Recently, ELISA method has been developed for the anti-DFS70 detection. Objective: We aimed to investigate the presence of anti-DFS70 antibodies in SLE and non-SLE patients using IIF assay and ELISA. Methods: We evaluated 45 SLE patients who fulfilled the Systemic Lupus International Collaborating Clinics (SLICC) classification criteria, SLEDAI score >5; 15 patients with atopic dermatitis (AD) with IgE >200 IU/ml, and 30 healthy subject individuals. Anti-DFS70 antibodies were measured by ELISA and IIF assay (ANA-DFS70 Cytobeads). Differences in the anti-DFS70 prevalence in SLE and non-SLE patients were analysed using a chi-square test. The sensitivity, and specificity of ELISA were calculated by McNemar’s test. Results: The presence of anti-DFS70 antibodies measured by IIF assay was found in 11.1% of SLE and 4.4% of non-SLE patients (p-value 0.434), while anti-DFS70 measured by ELISA was found in 17.7% of SLE and 6.6% of non-SLE patients (p-value 0.197). There was no significant difference in detecting anti-DFS70 of the two methods (p.0.05).  The ELISA has a sensitivity of 85.7% and a specificity of 94% for anti-DFS70 detection. Conclusion: Anti-DFS70 was detected more frequently in SLE rather than in non-SLE patients measured using both ELISA and IIF. There is good agreement between ELISA and IIF assay for the anti-DFS70 detection.