No patients with severe proliferative lupus nephritis: a. very active renal histology with crescents or necrosis in more than 25% of glomeruli; or b. rapidly progressive glomerulonephritis (doubling of serum creatinine in less than or equal to 3 months); or c. severe impairment of renal function Cr greater than 2.5 mg/dL or GFR less than 50 mL/min measured by inulin clearance.