Methods: In this cross-sectional study, we measured S100A9, S100A12 and 14 cytokines in serum from children with ALL (n=150, including 27 with arthropathy) and JIA (n=238) by multiplexed bead array assay on a MAGPIX instrument using Luminex software. The gene discussed is S100A9; the disease is acute lymphoblastic leukemia.