 The purpose of this clinical research study is to learn whether Abatacept can treat and prevent lupus flares; specifically, in patients with active lupus flares in at least one of three organ systems: skin discoid lesions; inflammation of the lining of the heart pericarditis, or inflammation of the lining of the lung pleuritispleurisy; or inflammation of more than 4 joints arthritis. All participants will receive prednisone or prednisone-equivalent treatment in combination with study medication. The safety of this treatment will also be studied. 