C1q deposition in the renal allograft: a report of 24 cases

Abstract

C1q nephropathy is an uncommon glomerular disease characterized by dominant or codominant mesangial staining for C1q in the absence of systemic lupus erythematosus. There are no series in the literature addressing the significance of C1q deposition in the renal allograft. We retrospectively analyzed 24 patients, most of whom were white (83%) and male (63%), with a mean age at transplant of 31 years. None of the patients were diagnosed with C1q nephropathy in the native kidney or had any features of systemic lupus erythematosus. The mean time from transplant to detection of mesangial C1q deposits was 37 months (412 months in 71% of cases). Half of the patients had a preceding infection. The indication for biopsy was surveillance (63%) or graft dysfunction (37%). At biopsy, 52% had proteinuria (41g/day in only 17%). The mean creatinine was 1.8 mg per 100 ml. Only 9% developed hematuria and none had hypoalbuminemia. The glomerular pattern on light microscopy was mesangial hypercellularity (46%), focal segmental glomerulosclerosis (21%), or no lesions (33%). All cases showed intense (Z2 þ ) dominant (67%) or codominant (33%) mesangial staining for C1q on immunofluorescence. Mesangial electron-dense deposits were seen in 82% of cases. On follow-up (mean 1 year) of the 10 patients without rejection, most had stable creatinine with no or stable proteinuria, and none lost their graft. We conclude that C1q-dominant mesangial deposition in the renal allograft is a morphological pattern with no apparent clinical significance in the majority of patients. It is usually detected after the first year. The rate of preceding infection and the prevalence of proteinuria seem to be similar to the renal transplant recipients in general. Most cases show mesangial hypercellularity or no glomerular changes on light microscopy. Modern Pathology (2010) 23, 1080-1088; doi:10.1038/modpathol.2010.92; published online 14 May 2010 Keywords: C1q nephropathy; transplant; de novo glomerular disease; FSGS; proteinuria; mesangial hypercellularityIn 1982, Jones and Magil 1 reported five patients with proteinuria and nonsystemic mesangiopathic glomerulonephritis, one of whom had C1q codominant mesangial deposits. In 1985, Jennette and Hipp 2 introduced the term 'C1q nephropathy' and defined it as dominant or codominant mesangial staining for C1q in patients lacking clinical or serological evidence of systemic lupus erythematosus. In their report, which included 15 patients who presented in their second or third decade of life with nephrotic-range proteinuria, 100% of patients had proteinuria (range 1-24 g/day), 40% hematuria, 0% hypocomplementemia, and 0% positive antinuclear antibodies. The light microscopic findings varied from normal-appearing glomeruli to mesangial hypercellularity to endocapillary hypercellularity. On immunofluorescence (IF), all cases showed intense segmental or global mesangial staining for C1q, which was accompanied by equal or weaker staining for C3 and immunoglobulins. On electron microscopy, all cases showed mesangial ele...

Is Early Complement Activation in Renal Transplantation Associated with Later Graft Outcome?

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Fate of full‐house immunofluorescence staining in renal allograft: A case report

“…C1q nephropathy is defined as dominant or codominant mesangial staining for C1q without clinical or serological evidence of SLE . Said et al described the C1q deposition in renal allografts, and reported that four of 24 cases in their study exhibited IgG staining intensity similar to that of C1q. Additionally, a mesangial electron‐dense deposit was detected in 82% of patients.…”

Nefropatía C1q, Reporte de caso

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