Abstract： Objective To study the expression of cellular FLICE inhibitory proteins(c-FLIP)in peripheral blood B lymphocytes in patients with systemic lupus erythematosus (SLE)and its correlation with clinical features.Methods Blood samples were obtained from 53 patients with SLE and 30 normal human controls.Flow cytometry and ELISA were performed to measure the expression of c-FLIP in pefipheral blood B lymphocytes and serum levels of IL-4 and IL-10,respectively.Relevant laboratory examinations were carried out for these patients.SLE disease activity index(SLEDAI)score was calculated for patients.Results The positivity rate of c-FLIP in B lymphocytes was 3.11%±0.70%in 18 patients with active SLE.significantly higher than that in 35 patients with inactive SLE (0.78%±0.28%)and normaI controls(0.68%±0.12%),while no statistical difierence was found between inactive patients and controls(t=1.56,P＞0.05).In SLE patients,the expression of c-FLIP showed a positive correlation with SLEDAl score(r=0.96.P＜0.05),erythrocyte sedimentation rate(r=0.96,P＜0.01),serum level of C reactive protein(r=0.92.P＜0.01)and the titer of antinuclear antibodies(r=0.86,P＜0.01),whereas in 36 patients with leucopenia.a negative correlation was noticed between white blood cell count and the expression level of c-FLIP(r=-0.94,P＜0.0 1).The 23 patients with lupus nephritis had a higher level of c-FLIP than those without lupus nephritis(3.04%±1.09%vs 1.76%±1.09%,t=4.23,P＜0.05).Additionally.the expression of c-FLIP positively correlated with the serum level of IL-4 and IL-10(r=0.80,0.89.respectively,both P＜0.01).Conclusions In patients with active SLE,the expression of c-FLIP is upregulated in peripheral blood B lymphocytes,and positively correlated with the severity of SLE as well as the serum level of IL-4 and IL-10.The upregulation of c-FLIP in B cells might play a certain role in deficient apoptosis or clearance of activated B cells in SLE.