Soluble Fas molecule in the serum of patients with systemic lupus erythematosus.

The serum level of soluble Fas (sFas) molecules in 35 patients with SLE was determined by enzyme-linked immunosorbent assay (ELISA) and its relation to other lymphocyte activation markers and clinical parameters was examined. The level of sFas increased significantly compared to that in normal subjects, consistent with previous reports. There was a significant correlation between the level of sFas and that of sCD4, suggesting some relation between sFas and activation of CD4+ T cell. Patients with lymphopenia tended to have low levels of sFas, making it possible to hypothesize that sFas protects against apoptosis. Although the change in the level of sFas protects steroid therapy was variable, some relation to the differential activation of T cell subsets was suggested.