Objective: To quantify soluble Fas/APO-1 (sFas/APO-1) protein in the serum of patients with systemic lupus erythematosus (SLE) and juvenile rheumatoid arthritis (JRA).
Methods: Soluble Fas/APO-1 was quantified using a sandwich enzyme-linked immunosorbent assay. Disease activity in SLE patients was assessed by the SLE Disease Activity Index.
Results: Increased serum sFas/APO-1 levels were observed in only 1 of the 27 SLE patients (4%) and 3 of the 10 JRA patients (30%).
Conclusion: Increased levels of sFas/APO-1 occurred infrequently in SLE, and the levels were lower than 10 ng/ml. Increased levels of sFas/APO-1 are not specific for SLE. Soluble Fas/APO-1 is unlikely to be of major pathogenetic significance in SLE.