Abstract: Objective To investigate whether plasma from patients with systemic lupus erythematosus (SLE) inhibits the suppressive effects of mesenchymal stem cells (MSCs) on lupus B lymphocytes. Methods MSCs isolated and expanded from the bone marrow of healthy donors were co-cultured with B cells purified from the peripheral blood of SLE patients in the presence of fetal bovine serum or pooled plasma from SLE patients, and the proliferation and maturation of the B lymphocytes were analyzed. Results Co-culture with normal MSCs obviously inhibited the proliferation of lupus B cells and suppressed the maturation of B lymphocytes, which showed lowered expressions of CD27 and CD38. The pooled plasma from SLE patients significantly inhibited the suppressive effects of normal MSCs on B cell proliferation and maturation. Conclusion Plasma from SLE patients negatively modulates the effects of normal MSCs in suppressing lupus B cell proliferation and maturation to affect the therapeutic effect of MSC transplantation for treatment of SLE. Double filtration plasmapheresis may therefore prove beneficial to enhance the therapeutic effects of MSC transplantation for SLE.