Detection of plasma protein S and growth-arrest specific protein 6 and their clinical significance in systemic lupus erythematosus / 中华风湿病学杂志

ABSTRACT

Objective To investigate the significance of plasma protein S and growth-arrest specific protein 6 (Gas6) in systemic lupus erythematosus (SLE).Methods Sandwich enzyme-linked immunosorbent assay (ELISA) was used to measure the protein S and Gas6 in the plasma of 103 SLE patients and 40 healthy controls.Mann-Whitney U-test,x2-test and Spearman's rank correlation were used for statistical analysis.Results The plasma concentrations of protein S and Gas6 were both significantly [protein S30.6 (27.2,33.6) μg/ml,37.8(35.4,46.7) μg/ml,Z=6.04,P＜0.01; Gas6402.6(239.2,757.8) pg/ml,913.6(765.0,1 290.6) pg/ml,Z=4.26,P＜0.01] decreased in plasma of SLE patients than that in healthy controls.There was a positive correlation between levels of protein S and Gas6 (r=0.312,P=0.001).The level of protein S in SLE patients was positively correlated with hemoglobin (Hb),WBC,platelet blood platelet (PLT),C3 and C4 (r=0.209,0.264,0.264,0.362,0.280,P＜0.01 or P＜0.05).Plasma protein S level was also found to be negatively correlated with auto-antibodies such as anti-double strand DNA (anti-dsDNA) antibody,anticardiolipin (ACL),anti-nucleosome antibody (AnuA) or IgG (r=-0.197,-0.264,-0.226,-0.229,P＜0.01or P＜0.05).The plasma Gas6 level was positively associated with age,disease duration and C-reaction protein (CRP) (r=0.229,0.198,0.263,P＜0.01 or P＜0.05).Patients with decreased Gas6 level showed higher incidence of fever,rash and serositis.Patients with decreased WBC or positive for proteinuria also showed decreased Gas6 (P＜0.05).Conclusion Protein S levels are significantly decreased in plasma of SLE patients and is associated with a series of severe disease manifestations such as hematological involvement,decreased complements and the presence of auto-antibodies.Decreased Gas6 levels in SLE patients are observed and they are correlated with age,disease duration and certain clinical characteristics such as rash,renal involvement and inflammatory response.