Management of membranoproliferative glomerulonephritis type II with plasmapheresis.

Membranoproliferative glomerulonephritis type II (MPGN II) is a rare kidney disease identified microscopically by electron-dense deposits surrounded by complement component C3 in glomerular basement membranes. MPGN II usually leads to renal failure, and patients with MPGN II experience a high rate of recurrence following renal transplantation. No treatment modalities have been proven successful if recurrence does occur. The sera of most patients with MPGN II contain complement C3 nephritic factor (C3NF), an IgG autoantibody directed against C3 convertase (C3bBb) that results in constitutive breakdown of C3. C3NF may be important in the pathogenesis of the disease. Since C3NF is IgG, we predicted that C3NF could be removed from the serum through plasmapheresis. We describe the use of long-term plasmapheresis to maintain good renal function in a 15-year-old girl with rapidly progressive recurrent MPGN II. After 73 plasmapheresis procedures over 63 weeks, her serum creatinine remained stable, and her creatinine clearance trended upward. Serial biopsies of the transplanted kidney demonstrated persistent MPGN II but no development of tubular atrophy. During the course of therapy, serum C3NF activity decreased; furthermore, C3NF activity was detected in the removed plasma. We have shown that plasmapheresis is a safe and effective method for delaying the onset of chronic renal failure in recurrent MPGN II. The efficacy may be due to the removal of serum C3NF.