LJP 394 (abetimus sodium) is a unique drug that is specifically designed to lower production of antibodies to double-stranded DNA. These antibodies are believed to contribute to kidney damage in patients with Systemic Lupus Erythematosus (SLE). Rising levels of these antibodies seem to be associated with exacerbations of kidney disease that are known as "renal flares." Currently, anti-inflammatory and cytotoxic drugs are used to treat renal flares. Unfortunately, these drugs are often associated with certain unpleasant side effects. The purpose of this trial is to determine whether LJP 394 can delay or reduce the number of renal flares. It is possible that if renal flares can be delayed or reduced, patients may be able to take smaller amounts of anti-inflammatory or cytotoxic drugs and therefore suffer fewer of the side effects associated with these treatments.