Objective To detect the expression of BclGL in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE) and to investigate its significance.Methods Peripheral blood was obtained from 20 patients with active SLE (A-SLE),18 patients with inactive SLE (Ⅰ-SLE) and 30 healthy controls.Flow cytometry was performed to calculate the number of PBMCs,flow cytometry combined with annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining to determine the early apoptotic rates of PBMCs,fluorescence-based quantitative PCR and Western blot to measure the expression of BclGL mRNA and protein,respectively.The serum level of interferon (IFN)-α was determined by enzyme-linked immunosorbent assay (ELISA).Data were analyzed by using the software SPSS13.0.Mann-Whitney U-test or Kruskal-Wallis test was used for group comparisons.Pearson correlation coefficient test was applied to evaluate the relationship of BclGL expression with cell apoptotic rate and some clinical parameters.Results The number of PBMCs was significantly lower in patients with A-SLE than in those with Ⅰ-SLE and healthy controls ((0.16 ± 0.06) × 109/L vs.(0.27 ± 0.14) × 109/L and (0.34 ± 0.23) × 109/L,both P ＜ 0.01).Increased apoptotic rate of PBMCs was observed in patients with A-SLE compared with those with Ⅰ-SLE and healthy controls ((22.6 ± 1.1)％ vs.(16.4 ±0.9)％ and (10.1 ± 0.4)％,both P ＜ 0.01),and in patients with Ⅰ-SLE compared with the healthy controls (P ＜0.01).The mRNA and protein expressions of BclGL in PBMCs were both significantly higher in patients with ASLE than in those with Ⅰ-SLE and healthy controls (all P ＜ 0.01).A significant increase was observed in serum IFN-α level in the patients with SLE compared with the healthy controls ((32.5 ± 2.2) μg/L vs.(15.5 ± 1.3) μg/L,P ＜ 0.01).The mRNA expression of BclGL in PBMCs from patients with SLE was positively correlated with the apoptotic rate in PBMCs (r =0.486,P ＜ 0.01),SLE disease activity index score (r =0.496,P ＜ 0.01),titers of antinuclear antibodies (r =0.516,P ＜ 0.01) and serum IFN-o level (r =0.535,P ＜ 0.01),but was negatively correlated with complement C3 level (r =-0.515,P ＜ 0.01).Conclusions The increased expression of BclGL in PBMCs may contribute to the abnormal apoptosis in PBMCs,which in turn takes part in the pathogenesis of SLE.