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.