We collected synovial fluids from fourteen adult RA patients [median age (range) of 42 (22–79) years and female/male ratio of 8/6] and from twelve pediatric patients with oligoarticular (n = 9) or polyarticular (n = 3) JIA [median age (range) of 11 (4–17) years and female/male ratio of 9/3] to explore the potential role of CXCL8 processing in this disease context using our newly developed ISTAMPA technology. The gene discussed is CXCL8; the disease is juvenile idiopathic arthritis.