The elevated proportions of IL-17 producing FoxP3+CD4+ cells found in our cohort, may reflect either a specialization of Treg on Th17 cells in JIA as discussed by Campbell et al. for autoimmune diseases in general [8] or echo an increased plasticity of Treg towards the proinflammatory Th17 type [14]. Here, IL17A is linked to juvenile idiopathic arthritis.