Serum soluble Fas levels in patients with autoimmune rheumatic diseases

Objective: The role of the serum soluble Fas (sFAS) system is unclear in diagnosis of several autoimmune rheumatic diseases although there are present contradictory reports on the levels of serum sFas. We therefore assessed levels of sFAS in serum of patients with autoimmune rheumatic diseases. Patients and methods: We analyzed sFas levels and their relationship to clinical and laboratory data in patients with systemic lupus erythematosus (SLE, n = 32), rheumatoid arthritis (RA, n = 28), Sjögrenʹs syndrome (SS, n = 20) systemic sclerosis (SSc, n = 21), polymyositis/dermatomyositis (PM/DM, n = 15). Patients with osteoarthritis (OA, n = 20) and healthy volunteers (n = 20) were used as controls. Serum levels of sFAS were determined by ELISA. sFas levels greater than mean (normals) + 2 SD were considered as elevated. Results: The mean sFas values were found higher in RA, PM/DM and OA than in control although no differences were found in SSc and SS patients. The mean sFas levels in SLE patients were lower than healthy controls. Elevated sFas rates in RA, PM/DM and SS were found to be 21.4%, 60%, 10% higher than in healthy controls, respectively. sFas levels in SLE and SSc did not differ from control values. Mean sFas levels did not show significant difference between active and inactive patients in all disease groups except PM/DM, RA and OA. No correlations of sFas with relevant disease subsets, laboratory findings and treatment modalities were found. Conclusions: The findings indicate that the serum sFas molecule may provide a useful additional marker for presence and assessment of disease in patients with RA and PM/DM.