HMGB1 and chronic obstructive pulmonary disease: Patients with COPD tended to have higher sputum HMGB1 levels than patients without COPD, median 17 ng/mL (range 4–563 ng/mL) vs. median 7 ng/mL (range 0–300 ng/mL), p = 0.080, but plasma HMGB1 levels did not differ between the groups (p = 0.33).