Overall, B cell phenotype analysis of JIA patients suggests altered B cell activating triggering mechanisms (CD5, CD21 and CD23), higher trafficking susceptibility (CXCR5) and triggering of bone erosion (RANKL).44 45 Regarding T cells, several studies support a role of T cells in JIA pathogenesis. This evidence concerns the gene TNFSF11 and juvenile idiopathic arthritis.