Anti-Nuclear Antibody Staining Patterns in Juvenile Idiopathic Arthritis: Association of AC-1 Pattern and Elevated Titers with Uveitis.

Objective: This study aimed to investigate antinuclear antibody (ANA) staining patterns and titers in patients with juvenile idiopathic arthritis (JIA)-associated uveitis, idiopathic uveitis, and JIA without uveitis, in order to identify serologic profiles that may contribute to disease pathogenesis and guide clinical decision-making.

Methods: We analyzed patients with JIA and/or uveitis at our tertiary center with ANA titers ≥1/100. Patients were grouped as JIA-associated uveitis, JIA without uveitis, and idiopathic uveitis. Diagnoses followed International League of Associations for Rheumatology and standardization of uveitis nomenclature criteria. ANA testing was performed by indirect immunofluorescence on HEp-2 cells, and patterns and titers were evaluated per International Consensus on ANA Patterns guidelines. ANA profiles were compared across patient groups and JIA subtypes.

Results: Ninety-one patients were included: 21 (23%) with idiopathic uveitis, 12 (13.1%) with JIA-associated uveitis, and 58 (63.7%) with JIA without uveitis. The AC-1 pattern was present in all uveitis patients. The most common ANA patterns in JIA were AC-1 (65.7%), AC-4/5 (21.4%), and AC-2 (10%). ANA profiles differed across JIA subtypes (p<0.001), with AC-1 dominant in oligoarticular JIA (74.5%) and AC-4/5 in enthesitis-related arthritis (50%).

Conclusions: Our findings show that ANA pattern differences in JIA subtypes may provide significant clues regarding disease pathogenesis and clinical prediction. In particular, the prominence of the AC-1 pattern in JIA-associated uveitis may suggest a potential biomarker for the early identification of uveitis risk, which should be further explored in larger prospective studies.