Combination of TACI-IgG and anti-IL-15 treats murine lupus by reducing mature and memory B cells.

Clinical trials suggest that BAFF inhibitors such as atacicept (TACI-IgG) and belimumab (anti-BAFF antibody) could not reduce memory B-cell numbers, although they reduced the numbers of CD20(+) naïve B cells and activated B cells. In the present study, we explored the way to reduce memory B-cell numbers. First, we used TACI-IgG to treat murine lupus. We found that TACI-IgG was effective in reducing mature B cell numbers. Accordingly it controlled the level of the anti-dsDNA antibody in lupus-like mice. In addition, TACI-IgG up-regulated memory B cells in murine lupus. Furthermore, we found that TACI-IgG up-regulated IL-15 expression in lupus-like mice. Thus, the combination of TACI-IgG and anti-IL-15 antibodies was explored to understand their effects on the treatment of murine lupus. Compared to treatments with TACI-IgG or anti-IL-15 alone, the combination of TACI-IgG and anti-IL-15 antibodies efficiently ameliorated murine lupus phenotypes. The study provides hints for the clinical application of BAFF- and IL-15-specific therapeutic agents.