C1q in the Donor Kidney: A New Form of C1q Nephropathy
Angela M Wright, Samir Patel, Ahmed Gaber, Roberto Barrios, Lillian Gaber, Luan Truong. The Methodist Hospital, Houston, TX
Background: C1q glomerular deposition has been described in C1q nephropathy, subsets of traditionally classified glomerulonephritis, otherwise unclassifiable glomerulonephritis, and in renal biopsies for asymptomatic hematuria or proteinuria. This controversial classification is compounded by a lack of knowledge on C1q glomerular deposition in the general population.
Design: A total of 356 post-perfusion kidney donor biopsies between 2008-2011 were reviewed to assess the frequency of C1 glomerular deposition and its significance. The intensity (0-3+) and distribution (focal, segmental, global, diffuse, mesangial, peripheral) of C1q glomerular deposition were recorded by three independent observers and biopsies with at least focal segmental 1+ staining were correlated with staining of IgG, IgA, IgM, C3, C4, kappa/lambda light chains, donors' information and graft outcome.
Results: C1q glomerular deposition was noted in 17/356 biopsies (4.8%). Clinical data included: 14 deceased donors, 3 living donors, 4 females, 13 males, ages 16-62 years, 8 Caucasian, 9 Hispanic, 5 with hypertension, 1 diabetic, and 2 with extended donor criteria. Features of C1q glomerular deposition in the 17 biopsies included: 17 mesangial; 0 peripheral; average intensity 1.5+; 0 as an isolated finding; 4 with IgG (1.1+); 8 with IgA (1.6+); 16 with IgM (1.6+); 14 with C3 (1.6+); 1 with C4 (1+); 5 with kappa light chain (1.2+); and 5 with lambda light chain (1.6+). Electron microscopy was performed in 3 biopsies and showed mesangial electron dense deposits in each. Light microscopy showed no changes in 4, tubular atrophy/interstitial fibrosis in 7 (mean cortical surface area involvement 10.4%), mesangial hypercellularity in 6, enlarged glomerular size in 4, and enlarged urinary space in 4. Vascular intimal sclerosis was mild to moderate in 10 and not present in 7. Follow-up biopsies were done in 3 patients (0.5-2 months post-transplant): 1 had no change in IF staining pattern, 1 had complete loss of IF staining, and 1 had acute antibody-mediated rejection. One patient had 2 follow-up biopsies done (5 months and 1 year post-transplant) and showed loss of C1q staining, but progression of tubular atrophy/interstitial fibrosis of unknown etiology.
Conclusions: C1q glomerular deposition can be seen in the general population. This finding expands the spectrum of glomerular diseases characterized by C1q glomerular deposition. C1q glomerular deposition may disappear after transplantation and does not seem to adversely affect the short-term outcome of the renal transplant.
Category: Kidney (does not include tumors)
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 270, Wednesday Afternoon