Objective The apoptotic signaling pathway is obviously disordered in systemic lupus erythematosus (SLE). Natural IgM (nIgM) is important in clearing apoptotic cells and preventing them from triggering deleterious autoimmunity. B-1-and innate-like B-(ILBs) cells are the main nIgM producers. Human CD27+IgD+B cells (un-switched memory B cells) are considered ILBs. However, their functional properties in SLE remain unde ned.Methods Peripheral blood samples of 50 SLE patients and 50 healthy control were collected, and twelve SLE patients were assessed in a follow-up study. The amounts of CD27 + IgD + B cell was analyzed by ow cytometry. The IgM and IL-10 levels of CD27 + IgD + B cell were assessed by ELISPOT and qRT-PCR. SPSS 17.0 (SPSS, USA) was employed for data analysis. P<0.05 indicated statistical signi cance.Result 92.0% were females, 17-67 years. CD27 + IgD + B cell amounts are signi cantly decreased in SLE patients than healthy control (p<0.01). CD27 + IgD + B cell amounts were positively correlated with WBC(r=0.337, p=0.017), platelet count(r=0.396, p=0.004) and serum C3 levels(r=0.415, p=0.003), CD27 + IgD + B cell amounts showed negative correlations with serum creatinine levels(r=-0.285, p=0.045), SLEDAI(r=-0.724, p=0.000), anti-dsDNA(r=-0.477, p=0.000) and CRP(r=-0.398,p=0.004). The IgM and IL-10 levels of CD27 + IgD + B in SLE were decreased than healthy control (p<0.001), moreover CD27 + IgD + B cells are increased in SLE cases after treatment in SLE patients than before treatment(p<0.001). Conclusion CD27 + IgD + B cell amounts are signi cantly decreased and it was correlated with clinical and immunological features in SLE patients. CD27 + IgD + B cells had impaired function regarding IgM and IL-10 production in SLE, however, CD27 + IgD + B cells amounts are recovered in SLE cases with treatment-related disease remission.