This study is designed to assess the effectiveness of eculizumab in recipients of kidney transplantation with donor-specific antibodies (DSA) and worsening kidney function and to assess if eculizumab improves endothelial cell injury in the kidney.

The investigators hypothesize that complement inhibition with eculizumab will reduce allograft injury, resulting from less complement-mediated injury of endothelial cells and less endothelial cell activation.