Abstract:

Objective: To investigate the clinical and pathological features of complement C3 (C3) glomerulonephropathy. Methodology: 17 Chinese patients diagnosed with C3 glomerulonephropathy by clinical and histopathological methods (light microscopy, immunofluorescence and electron microscopy ) were enrolled. The clinical data and pathologic features of 17 patients were analyzed. Results: There were 11 males and 6 females with average age of 34.1±19.1 years (10~75) and renal history 1.3±1.2 years (1week~8 years）. Most patients had no obvious predisposing causes. The initial symptoms were edema and proteinuria in most patients. Among which, 5 had nephritic syndrome and 3 had rapidly progressive glomerulonephropathy. Urinary analysis showed proteinuria of 3.1±3.2g/d with micro-hematuria (64.7%) ( including 5 gross hematuria).  Hypertension were found in 10 cases and elevated serum creatinine in 4. There were 11 patients with low complement C3 and 5 with anemia. C3 nephritic factor (C3NF) were carried out in 5 cases，only 1 patients were positive. Renal biopsy revealed membrane proliferative glomerulonephritis (MPGN) in 12 patients（70.6%）with endothelial and mesangial proliferative, some with thickened glomerular basement membrane (GBM). Granular C3 were deposited along with GBM，but absence of substantial immunoglobulin by immunofluorescence (IF). Electron microscopy observation found the presence of subendothelial and mesangial electron-dense deposits. There were 15 patients followed-up for 1 month to 5 years，2 was complete remission and 11 had partial remission with immunosuppressive therapy. Conclusion: C3 glomerulonephropathy was newly recognized in recent years. There was no significant  clinical features of  this disease. Immunofluorescence evidence showed C3 predominantly deposited within the GBM. Electron microscopy was valuable in the diagnosis. There was no effective treatment of C3 glomerulonephropathy. Further investigation of mechanism is needed.

Key words: C3 glomerulonephritis,  renal biopsy, , C3 nephritic factor, , pathology