The significance of anti-DFS70 autoantibody in oligoarticular juvenile idiopathic arthritis and pediatric uveitis

Introduction and aims: Juvenile idiopathic arthritis is the most common rheumatologic disease in childhood and at the same time it is one of the most common chronic diseases in childhood. The most common subtype is oligoarticular type, which accounts for 50% of all JIA cases. Since JIA is of autoimmune origin, some autoantibodies are also important in diagnosis and follow-up. These autoantibodies are often directed against the cell nucleus and are termed anti-nuclear antibodies (ANA). The most commonly used method to determine which specific antigen is developing against the specific antigen in patients positive for indirect immunofluorescence (IIF) test is the blot method in which extractable nuclear antigens (ENA) are detected. Anti-DFS70 is a common pattern in ANA IIF. Few studies with anti-DFS70 autoantibodies have found that this antibody positivity is more common in the healthy population. In a pediatric study, it was suggested that anti-DFS70 might be associated with uveitis. The aim of this study was to determine the prevalence of anti-DFS70 autoantibody in healthy individuals, oligoarticular JIA patients and pediatric idiopathic uveitis patients and to determine the demographic, clinical and laboratory characteristics of the patient population in our region. Materials and methods: This study is a cross-sectional study which is between oligoarticular JİA patients (diagnosed according to International League of Associations for Rheumatology criteria), idiopathic uveitis and healty individuals. Patients who applied to Dokuz Eylul University Faculty of Medicine Pediatric Rheumatology outpatient clinic between October 2018 and September 2019 were included in the study and blood samples were taken and patient data forms were filled. Analysis was done between of ANA and anti-DFS70 autoantibody positivity with presence of uveitis, presence of JIA, number of joint involvement, time to diagnosis of uveitis, use of biological agents, use of systemic steroid and the presence of allergic diseases. xiii Results: The study group was divided into four groups: oligoarticular JIA (group 1), oligoarticular JIA and uveitis (group 2), idiopathic uveitis (group 3) and control group (group 4) without rheumatologic disease. The mean age of the group was 9.73 ± 4.39 years. Of the participants, 86 (78.2%) were ANA positive and 24 (21.8%) were ANA negative. 35 (31.8%) of the participants were anti-DFS70 positive and 75 (68.2%) were anti-DFS70 negative. When presence of uveitis and anti-DFS70 autoantibody positivity is analyzed, it was found that anti- DFS70 autoantibody positivity did not constitute a risk factor for uveitis (p>0.05). Similarly, ANA positivity did not appear to be a risk factor for uveitis (p> 0.05). In the evaluation of allergic disease, both ANA positivity (p <0.05) and anti-DFS70 positivity (p <0.01) increased the risk of allergic disease. Conclusion: In our study, the relationship between uveitis and anti-DFS70 was investigated and it was determined that anti-DFS70 positivity did not cause uveitis development. Therefore, considering that uveitis may be an important complication in JIA, it may be considered that the frequency of eye examinations can be performed at longer intervals when anti-DFS70 positivity is detected in oligoarticular JIA patients. In our study, the frequency of allergic diseases was found to be higher in the group with anti-DFS70 positivity. This is an important finding for future studies.