Soluble Fas (APO-1, CD95) and soluble Fas ligand in rheumatic diseases

Objective. To assess levels of soluble Fas (sFas) and soluble Fas ligand (sFas-L) in sera from patients with various rheumatic diseases: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), mixed connective tissue disease (MCTD), and Sjogren's syndrome (SS). Methods. Levels of sFas and sFas-L were determined by a sandwich enzyme-linked immunosorbent assay. Results. In SLE, PM/DM, MCTD, and SS, sFas levels were significantly higher compared with normal controls, Levels of sFas in the SLE patients were significantly higher than in patients with other rheumatic diseases, Levels of sFas-L were significantly increased in SS patients, SLE and RA patients with high levels sFas-L tended to have high levels of sFas, while sFas and sFasL levels did not correlate in patients with other diseases, In some of the SLE patients, sFas and sFas-L levels decreased following steroid therapy. Conclusion. Serum sFas and sFas-L levels were significantly higher in some rheumatic disease patients. Since these changes are complex in these rheumatic diseases, it may be difficult to directly relate sFas and sFasL to their pathogenesis.