SAT0645 ANTI-DFS70 AUTOANTIBODIES INDUCED BY ANTI-TNF THERAPY IN RHEUMATOID ARTHRITIS AND SPONDYLOARTHRITIS PATIENTS
Authors: Teresa Carbone, Carmela Esposito, Ornella Mercuro, Antonio Carriero, Valentina Picerno, Maria Carmela Padula, Angela Padula, Vito Pafundi, Salvatore D’angelo
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> anti-DFS70 antibodies (anti-DFS70ab) were recently described as biomarkers clinically useful to discriminate Systemic Autoimmune Rheumatic Diseases (SARD) from non-SARD patients, especially if no concomitant SARD-specific autoantibodies were found. Several unanswered questions concerning the biological significance of this autoantibodies still remain. Objectives: to evaluate the prevalence of anti-DFS70ab in Rheumatoid Arthritis (RA) and Spondyloarthritis (SpA) patients and the influence of anti-TNF therapy on their development. Methods: sera from adult RA (n= 100) and SpA (n= 105) patients, included psoriatic arthritis, fulfilling ACR/EULAR 2010 and ASAS 2011 criteria, respectively, were studied for anti-DFS70ab as measured by IIF, then confirmed by immunoblotting. Medical history, demographic and clinical data were collected at enrolment. <h3>Results:</h3> the prevalence of anti-DFS70ab was 4.00% (4/100) in the RA and 4.76% (5/105) in SpA cohort. All anti-DFS70ab in RA patients were monospecific, while only 1 sample in SpA showed concomitant anti-centromere positivity. The findings for the anti-DFS70ab positivity revealed no statistical differences between the groups (<i>p</i>&gt;0.05). In RA cohort, there were no differences between anti-DFS70ab positive and negative patients regarding the F/M <i>ratio</i> (F/M, 3/1 <i>vs</i> 84/12, <i>p</i>&gt;0.05), mean age (50.2±12.4 <i>vs</i> 55.6±11.7 yrs, <i>p</i>&gt;0.05) and disease duration (18.2±15.2 <i>vs</i> 14.0±9.9 yrs, <i>p</i>&gt;0.05). In SpA group, no significant differences were found between patients with and without anti-DFS70ab in F/M <i>ratio</i> (3/2 <i>vs</i> 43/57, <i>p</i>&gt;0.05) and regarding disease duration (18.8±7.7 <i>vs</i> 19.0±20 yrs, <i>p</i>&gt;0.05) while the mean age of anti-DFS70ab patients was significantly higher than the negatives (66.8±10.4 vs 53.5±15.0 yrs, p&lt;0.05). Serological and clinical data of anti-DFS70ab positive patients were summarized in Table 1. In our cohort, all anti-DFS70ab were negative before initiating biologics. <h3>Conclusion:</h3> based on our findings, detection of anti-DFS70ab reactivity cannot completely exclude the suspicion of SARD, especially for RA and SpA. In addition, the rate of anti-DFS70ab positivity resulted higher in RA and SpA patients than previously observed in a cohort of samples from outpatients clinics (2.1%) [1]. Immunogenicity of anti-TNF therapy has been also addressed in this study, showing that all detected anti-DFS70ab were induced by anti-TNF therapy. Further studies are needed to support these preliminary data. <h3>References</h3> [1] Carbone T. et al. Prevalence and serological profile of anti-DFS70 positive subjects from a routine ANA cohort. Scientific Report. 2019, In press. <h3>Disclosure of Interests:</h3> Teresa Carbone: None declared, carmela esposito: None declared, ornella mercuro: None declared, Antonio Carriero: None declared, valentina picerno: None declared, Maria Carmela Padula: None declared, Angela Padula Speakers bureau: Lilly Italia EMS, vito pafundi: None declared, Salvatore D'Angelo: None declared