Serum heme oxygenase (HO)-1 and ferritin levels in all the patients studied. Filled triangles stand for patients with active hemophagocytic syndrome (HPS). Open circles stand for those with active adult-onset Still's disease (ASD). The horizontal dotted line indicates 500 ng/ml of ferritin, which was determined on the basis of revised Diagnostic Guidelines for hemophagocytic lymphohistiocytosis [22,25], and the vertical dotted line indicates the arbitrary cutoff value 10 ng/ml of HO-1.
Kirino et al. Arthritis Research & Therapy 2005 7:R616 doi:10.1186/ar1721