Abstract: Objective To investigate the relationship between plasma concentration of osteopontin (OPN) and disease activity in systemic lupus erythematosus (SLE).Methods The plasma concentration of OPN in 28 healthy controls and 38 SLE patients was measured by enzyme-linked immunosorbent assay.Results The plasma concentration of OPN was significantly higher in SLE patients compared to that in the healthy controls (420±203 ng/mL vs 73±14 ng/mL,P<0.001),in the patients with proteinuria compared to that in the patients without proteinuria (623±88 ng/mL vs 288±135 ng/mL,P<0.001),in the patients with active disease compared to that in those with inactive disease (529±143 ng/mL vs 185±66ng/mL,P<0.001),in the patients before treatment compared to that in the patients after treatment (556±130 ng/mL vs 142±22 ng/mL,P<0.001).The plasma concentration of OPN in patients with arthritis was not different from those without arthritis (489±153 ng/mL vs 375±222 ng/mL,P>0.05).Plasma concentration of OPN showed a significant positive correlation with systemic lupus erythematosus disease activity index (SLEDAI) (r=0.93,P<0.001),but a significant negative correlation with serum C3 level (r=-0.49,P<0.05).There was no correlation between plasma concentration of OPN and antinuclear antibody titre,erythrocyte sedimentation rate,or serum level of C4.MConclusions These data show that plasma OPN level has some correlation with the SLE activity,renal damage and progression or amelioration of SLE.OPN could be involved in the pathogenesis of SLE.

Key words: Lupus erythematosus,systemic, Osteopontin, Enzyme-linked immunosorbent assay