JIA children, compared to controls, showed significantly higher concentrations of plasma TNF-α (95.9 ± 46.1 versus 22.7 ± 3.8 pg/mL; p = 0.002) and IL-6 (19.3 ± 3.2 versus 11.8 ± 1.8 pg/mL; p = 0.04), while there were no differences in IL-1β, IL-1ra and progenitor cell mobilizing factors (bFGF, G-CSF, PDGF-bb, VEGF and SCF). This evidence concerns the gene IL1B and juvenile idiopathic arthritis.