tment in ratio to the mean of control in the bone marrow, and spleen. Values are meanSEM; ns, nonsignificant, P>0.05, P<0.05, P<0.01, P<0.001, post-hoc test. Abbreviations: Bz, PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19723632 bortezomib; CD20, anti-mouse CD20 antibody; Int, Integrin blocking antibodies, anti-LFA1 and anti-VLA4 antibodies. doi:10.1371/journal.pone.0135081.g004 10 / 17 Long-Term Plasma Cell Depletion Ameliorates SLE Fig 5. B cell depletion maintenance therapy after short-term depletion of B and plasma cells with ant-CD20 and bortezomib improves the disease in NZB/W F1 mice. Mice were treated with anti-CD20 and bortezomib alone or continuous B cell depletion without bortezomib or treated as STD followed by BCD maintenance therapy with anti-CD20. Serum IgM and IgG anti-dsDNA antibody levels in treated and untreated mice, as measured by ELISA. Proteinuria in treated and untreated mice. Statistical differences between treated and untreated mice were analyzed using the post-hoc test. Survival curves for treated and untreated NZB/W F1 mice. Abbreviations: STD, Short-term depletion; BCD; B cell depletion. doi:10.1371/journal.pone.0135081.g005 without bortezomib did not delay the onset of proteinuria but induced a slight reduction of the proteinuria levels, which became significant at weeks 32 and 36. However, only the combination of STD with continuous BCD using anti-CD20 antibody PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19723293 promoted a significant delay in the onset of proteinuria followed by a persistent decrease in proteinuria levels from week 36 to the end of the observation period as compared to untreated mice, and mice treated with BCD or STD alone over time . In line with the delayed onset and development of proteinuria, the mice treated with STD alone, BCD, and STD in combination with continuous BCD therapy survived longer than untreated mice. Likewise, mice treated with initial STD plus continuous BCD therapy had higher survival rates than those treated with STD and BCD alone . These data show that continuous BCD therapy after efficient B cell and plasma cell depletion reduces the autoantibody levels and ameliorates nephritis, promoting the survival of lupus-prone mice. 11 / 17 Long-Term Plasma Cell Depletion Ameliorates SLE Discussion and Conclusions Autoantibodies play a crucial role in the pathogenesis of many autoimmune diseases. Therefore, their reduction or removal is an important therapeutic goal. Previously, we showed that autoantibodies can be generated by two different plasma cell compartments. The first consists of short-lived plasmablasts and plasma cells recently generated from activated B cells. Therapies targeting B cells block the generation of these newly generated order Celgosivir autoantibody-secreting plasmablasts, and immunosuppressive drugs that affect proliferating B cells and plasmablasts can also eliminate this compartment. The second compartment consists of long-lived plasma cells that reside in survival niches in the bone marrow and in inflamed tissues. In contrast to the first compartment, the second is resistant to B-cell targeting and conventional immunosuppressive therapies. Compelling evidence suggests that these autoreactive LLPCs can drive autoantibody-mediated inflammation, the maintenance of autoimmunity and refractory autoimmune disease. Therefore, there is an urgent need to define more effective ways to eliminate the long-lived plasma cell compartment in autoimmune diseases. In this study, we explored the short-term effects of different depletion strategies, targeting B cells alone or in comb