Systemic juvenile idiopathic arthritis (systemic JIA) is the most severe form of JIA, often with persistent chronic arthritis, joint damage, and disability along with systemic features (spiking fever, rash, hepatosplenomegaly, and serositis) and raised levels of markers of inflammation. High-dose steroid treatment is often toxic and other treatments such as methotrexate and tumour necrosis factor inhibitors are relatively ineffective. Interleukins 1 and 6 have been implicated in the pathogenesis and preliminary studies have shown clinical responses to antibodies against these interleukins. Now successive papers in the New England Journal of Medicine …