A Study to Evaluate the Safety of Rituximab Retreatment in Subjects With Systemic Lupus Erythematosus

Inclusion Criteria: * Subjects with systemic lupus erythematosus (SLE) who participated and satisfactorily completed their Week 52 evaluation in Study U2971g. * For partial clinical response (PCR) or nonclinical response (NCR), active disease at screening as defined by one or more domains with a British Isles Lupus Assessment Group (BILAG) A score or 2 or more domains with a BILAG B score. Exclusion Criteria: * Subjects who were withdrawn from study U2971g because of protocol non-compliance or for safety issues. * Any safety concern potentially attributed to rituximab that in the investigator's opinion would jeopardize subject safety. * Subjects who were withdrawn from study U2971g and received rituximab rescue therapy outside of the protocol. * Subjects, that in the investigator's opinion, have not demonstrated any clinical improvement by Week 52 in study U2971g and in whom the proposed therapy would represent risk without benefit. * Unstable subjects with thrombocytopenia experiencing or at high risk for developing clinically significant bleeding or organ dysfunction requiring therapies such as plasmapheresis or acute blood or platelet transfusions. * Pregnant women or nursing (breastfeeding) mothers. * History of severe, allergic, or anaphylactic reactions to humanized or murine monoclonal antibodies. * Known active infection of any kind (excluding fungal infection of nail beds) or any major episode of infection requiring hospitalization or treatment with intravenous (IV) antibiotics within 8 weeks of screening or oral antibiotics within 2 weeks prior to screening. * History of cancer, including solid tumors, hematological malignancies, and carcinoma in situ. * Major surgery within 4 weeks prior to screening. * Intolerance or contraindication to oral or IV corticosteroids. * Positive hepatitis B surface antigen (BsAg) or hepatitis C serology. * Receipt of a live vaccine within 28 days prior to treatment.