In systemic vasculitis, high serum HMGB1 levels were observed in Kawasaki disease, immunoglobulin (Ig)A vasculitis, and in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, especially in granulomatosis with polyangiitis (GPA) with granulomatous manifestations [24–27]. Here, HMGB1 is linked to vasculitis.