ELEVATION OF THE SERUM FAS LIGAND IN PATIENTS WITH HEMOPHAGOCYTIC SYNDROME AND DIAMOND-BLACKFAN ANEMIA

Fas ligand (Fast) is a membrane protein that is expressed in activated T cells and natural killer cells. Fast binds to Fas on target cells a nd induces apoptosis. There exists a soluble form of Fast (sFasL), and sFasL also induces apoptosis of Fas-bearing cells. The serum sFasL co ncentrations were reported to be elevated in patients with large granu lar lymphocytic leukemia and natural killer cell lymphoma. In this stu dy, we have measured serum sFasL concentrations in other hematological disorders, including severe aplastic anemia (SAA), hemophagocytic lym phohistiocytosis (HLH), and Diamond-Blackfan anemia (DBA). The serum s FasL concentration of age-matched healthy controls was 0.16 +/- 0.11 n g/mL (mean +/- SD, n = 22). The serum sFasL levels in the patients wit h HLH and DBA were 3.75 +/- 3.82 (n = 19; P < .0001, HLH v control) an d 2.76 +/- 2.43 ng/mL (n = 6; P = .012, DBA v control), respectively. Serum interferon-gamma concentration was elevated in the patients with HLH (1.61 +/- 2.62 ng/mL) but not in those with DBA (below the detect able level). These results suggest that the Fas-FasL system plays a ro le, at least in part, in the pathophysiology of HLH and DBA, (C) 1998 by The American Society of Hematology.