While the use of serum HMGB1 as biomarker is judged differently between GPA and AAV [58,61], locally acting necrosis- and inflammation-derived HMGB1 could support the granulomatous inflammation via recruitment of neutrophils as well as monocytes, dendritic cells, and B cells [62,63], possibly even supporting autoimmune responses, at least in GPA. The gene discussed is HMGB1; the disease is granulomatosis with polyangiitis.