Immunological Profile in Juvenile Idiopathic Arthritis

Patients with JIA were enrolled at the University Medical Center Utrecht (The Netherlands) (Supplementary file 1). A total of nine JIA patients were included in this study. Of these, n=2 were diagnosed with extended oligo JIA, n=2 with rheumatoid factor negative poly-articular JIA, and n=5 with oligo JIA, according to the revised criteria for JIA (Petty et al., 1998 (link)). The average age at the time of inclusion was 13.1 years (range 3.2–18.1 years) with a disease duration of 7.3 years (range 0.4–14.2 years). Patients included for CyTOF and TCR sequencing analysis of two affected knee joints were all treated with non-steroidal anti-inflammatory drugs (NSAIDs) or methotrexate, but no biologicals at the time of sampling. For sequential TCR sequencing analysis, we included patients with a relapsing disease course. At the first time point, all patients were treated with NSAIDs or methotrexate, but no biologicals. During the follow-up (after experiencing a relapse of disease), patients were treated with disease-modifying anti-rheumatic drugs (leflunomide) and/or biologicals (humira).
PB of JIA patients was obtained via veni-puncture or intravenous drip, while SF was obtained by therapeutic joint aspiration of affected joints. Informed consent was obtained from all patients either directly or from parents/guardians when the patients were younger than 12 years of age. The study was conducted in accordance with the Institutional Review Board of the University Medical Center Utrecht (approval no. 11-499/C), in compliance with the Declaration of Helsinki. PB from n=3 healthy children (average age 15.1 years with range 14.7–15.4 years) was obtained from a cohort of control subjects for a case-control clinical study (Supplementary file 1).