Approximately 50 adult patients, 25 with lupus nephritis 25 control patients who have greater than 1 gram per day proteinuria and non-SLE diagnoses, and who qualify for this study based upon the stated inclusion/exclusion criteria will be recruited from the Glomerular Center at Columbia University Medical Center.

Inclusion Criteria:

• Adults between 18 and 80 years of age, inclusive
• Diagnosis of SLE by ACR criteria and biopsy-proven ISN/RPS Class III or IV lupus glomerulonephritis within 2 years

• Persistently active nephritis defined as proteinuria greater than or equal to 1.0 g/day for 3 months or more, AND at least 1 of the following:

  • Hematuria (greater than or equal to 5 RBC/hpf) on 2 or more urinalyses done greater than or equal to 2 weeks apart
  • anti-dsDNA positive or anti-Smith positive, or
  • low C3 or C4 complement level. (d) Stable immunosuppression consisting of mycophenolate mofetil (MMF) 13 g/day with/without corticosteroids up to prednisone equivalent of 15 mg/day, or azathioprine 13 mg/kg/day with/without corticosteroids up to prednisone equivalent of 20 mg/day.
• Stable dose of ACE inhibitor/ARB for 4 weeks prior to study enrollment, unless previously intolerant to or having a contraindication to ACE inhibitors and ARBs
• If using oral corticosteroids, must be on a stable dose equivalent to less than or equal to 15 mg/day of prednisone for at least 4 weeks prior to study enrollment. If currently not using corticosteroids, the subject must not have received oral corticosteroids for at least 4 weeks prior study enrollment.
• Clarification of inclusion criteria for controls: Any patient with an idiopathic glomerular disease who does not have lupus nephritis. This includes patients with minimal change disease, membranous nephropathy, focal segmental glomerulosclerosis, and IgA nephropathy.

Exclusion Criteria:

• B-cell depletion therapy in past 1 yr, or evidence of persistent B cell depletion at the time of screening.
• Received an investigational drug (including vaccines) or used an investigational medical device within 3 months of study enrollment or within 5 half-lives of agent, whichever is longer.