Increased IL-18 concentrations in the serum of HPS patients. (A) Total IL-18 and (B) IL-18BP concentrations were measured and (C) free IL-18 concentrations were calculated in HPS patients during the acute phase or after remission of the disease as well as in control groups composed of healthy volunteers (healthy controls) or patients suffering from infection, malignant hemopathy, or cancer without HPS (disease controls). Box plot representation, horizontal line within boxes represents median. ○ indicates outside values. *P < .01, **P ≤ .001 compared with respective controls.