This study will examine the safety and effects of the monoclonal antibody MRA in patients with systemic lupus erythematosus (SLE). Antibodies normally fight invading organisms. In autoimmune diseases, such as lupus, however, antibodies attack the body s own tissues. MRA is an antibody manufactured in the laboratory that blocks the action of interleukin-6 (IL-6), a substance that increases antibody production and is involved in inflammation that may cause organ damage in SLE.