IL1B and systemic-onset juvenile idiopathic arthritis: Therefore, SJIA and AoSD likely represent a continuum of the the same disease entity.41,42 A distinctive feature of SJIA is its strong association with macrophage activation syndrome, characterised by an uncontrolled activation of macrophages releasing a high amount of pro inflammatory cytokines; particularly IL-1-related cytokines (IL-1β, IL-6, lL-18).