Inclusion Criteria:

• Male or female subjects between the ages of 18 and 60 years, inclusive
• Meet at least 4 of 11 American College of Rheumatology (ACR) Revised Classification Criteria for SLE

• Have at least one of the following conditions defining severe steroid refractory disease:

  a) Lupus nephritis - Subjects must have severe disease, defined as meeting criteria for BILAG renal category A, and be corticosteroid dependent while receiving at least 6 months of pulse CTX at doses of 500 to 1000 mg/m2 every 4 weeks or MMF at of 2 g/day or greater. If nephritis is to constitute the sole eligibility, a renal biopsy performed within 11 months of the date of screening must show ISN/RPS 2003 classification of lupus nephritis Class III or IV disease. A renal biopsy must demonstrate the potential of a reversible (non-fibrotic) component. b) Visceral organ involvement other than nephritis - Subjects must be without mesenteric vasculitis. The subject must be BILAG cardiovascular/respiratory category A, vasculitis category A, or neurologic category A, and be corticosteroid dependent while receiving at least 3 months of oral (2 to 3 mg/kg/day or greater) or IV CTX (500 mg/m2 or greater every 4 weeks). c) Cytopenias that are immune-mediated - Subjects must be BILAG hematologic category A and be corticosteroid dependent while receiving at least one of the following: azathioprine at 2 mg/kg/day or greater for at least 3 months, MMF at 2 g/day or greater for more than 3 months, CTX at 500 mg/m2 or greater intravenously every 4 weeks or 2 mg/kg/day orally for at least 3 months, cyclosporine at 3 mg/kg/day or greater for at least 3 months, or have had a splenectomy. d) Mucocutaneous disease - Subjects must meet BILAG mucocutaneous category A and be corticosteroid dependent while receiving at least 1 of the following: azathioprine at 2 mg/kg/day or greater for at least 3 months; methotrexate at 15 mg/week or greater for at least 3 months; CTX at 500 mg/m2 or greater intravenously every 4 weeks or 2 mg/kg/day or greater orally for at least 3 months, cyclosporine at 3 mg/kg/day or greater for at least 3 months, or MMF at doses 2 g/day or greater for at least 3 months. e) Arthritis/myositis - Subjects must meet BILAG musculoskeletal category A and be corticosteroid dependent while receiving at least one of the following: azathioprine at 2 mg/kg/day or greater for at least 3 months, methotrexate at 15 mg/week or greater for at least 3 months, CTX at 500 mg/m2 or greater intravenously every 4 weeks or 2 mg/kg/day or greater orally for at least 3 months, MMF at 2 g/day or greater for at least 3 months, or cyclosporine at 3 mg/kg/day or greater for at least 3 months.

• Have the ability and willingness to provide written informed consent. In case of lupus cerebritis, a person designated by the subject may give consent.
• Must be ANA positive

Exclusion Criteria:

• HIV positive status
• Any active systemic infection
• Hepatitis B surface antigen positive
• Hepatitis C PCR positive
• Use of immunosuppressive agents for other indications other than SLE
• Any comorbid illness that in the opinion of the investigator would jeopardize the ability of the subject to tolerate therapy
• For lupus nephritis: renal biopsy, performed within 11 months of the screening date, showing Class I, II, or V disease or Class III or IV disease in conjunction with total sclerosis of 50% or more of the glomeruli
• Ongoing cancer. Patients with localized basal cell or squamous skin cancer are not excluded.
• Pregnancy, unwillingness to use acceptable means of birth control, or unwilling to accept or comprehend irreversible sterility as a side effect of therapy
• Psychiatric illness or mental deficiency not due to active lupus cerebritis making compliance with treatment or informed consent impossible
• Hemoglobin adjusted diffusion capacity test (DLCO) less than 30% at screening
• Resting left ventricular ejection fraction (LVEF) 40% or less as evaluated by echocardiogram
• History of an allergic reaction or hypersensitivity to Escherichia coli recombinant proteins, CTX, or any part of the investigative or control therapy
• SGOT/SGPT greater than 2 x the upper limit of normal, unless due to active lupus
• ANC 1000 or greater if not due to active SLE
• Subdural hematoma or any active intracranial bleeding documented within 30 days of the screening visit
• Failure to be approved for participation in this study by the SCSLE Protocol Eligibility Review Committee
• Positive tuberculin skin test
• Presence of mesenteric vasculitis