MPO and juvenile idiopathic arthritis: To determine whether NETs are generated in JIA, we examined serum from JIA patients (n = 30) (Supplementary Table 1) for presence of NETosis markers: cell-free DNA (DNA-histone complexes), myeloperoxidase (MPO), neutrophil elastase, LL37 and citrullinated histone H3 (citH3) relative to healthy donors.