The role of CD4 + CD25 + T cells in autoantibody production in murine lupus

Summary Systemic lupus erythematosus (SLE) is a chronic, systemic autoimmune disease characterized by the loss of tolerance to self‐antigen. Because it is currently not known if regulatory T (T reg ) cells are involved in the pathogenesis, we determined the frequency of CD4 + CD25 + T cells and assayed the related gene expression levels in CD4 + CD25 + T cells isolated from both lupus mice (NZB/NZW F 1 ) and normal control mice (DBA2/NZW F 1 ). The results showed that the frequency of CD4 + CD25 + T cells in lupus mice was lower than that of normal mice. Except for the high expression level of interleukin (IL)‐10 mRNA, CD4 + CD25 + T cells from lupus mice expressed normal forkhead box P3 (Foxp3) and transforming growth factor (TGF)‐β mRNA, and exerted suppressive functions. Furthermore, we depleted CD25 + T reg cells of non‐autoimmune mice with anti‐CD25 antibody and broke their tolerance with apoptotic cell‐pulsed dendritic cells for the follow‐up of autoantibody levels. The mice in the CD25 + cell‐depleted group had higher titres of anti‐double‐strand/single‐strand DNA antibodies than those of the isotype control antibody‐treated group. These findings indicated that CD4 + CD25 + T cells might be involved in the regulatory mechanism of autoantibody production.