Abstract: Abstract Objective：To investigate the association between serum level of osteopontin (OPN), disease activity and organ damage of systemic lupus erythematosus (SLE). Methods：Six-three SLE patients and 20 healthy, age- and sex-matched controls were enrolled in this study. According to the systemic lupus erythematosus disease activity index (SLEDAI)，patients were divided into renal damage group (0-8 score，n=32) and without renal damage group (≥9 score，n=31). According to the interstitial pulmonary fibrosis index, patients were divided into interstitial lung disease (ILD) group (n=22) and without ILD group (n=41). Patients were also divided into heart damage group (n=25) and without heart damage group (n=38) according to the electrocardiogram，echocardiogram and cardiac enzyme results. Based on hematological results, patients were divided into with cytopenia group (n=45) and without cytopenia group (n=18). The serum level of OPN was detected by enzyme-linked immunosorbent assay (ELISA) in patients of groups. Results：The serum level of OPN was significantly higher in SLE group than that of healthy controls (P<0.05 or P＜0.01). The serum level of OPN was significantly higher in patients with renal damage, lung interstitial disease, heart damage and cytopenia than that of patients without organ involvement in SLE (P＜0.01). The serum level of OPN was significantly positively correlated with SLEDAI in SLE patients (r=0.982，P＜0.01). Conclusion：OPN plays a role in the pathogenesis of SLE and is related to the disease activity and organ damage. OPN may serve as an active disease laboratory marker of SLE.

Key words: lupus erythematosus, systemic, osteopontin