Significance of glomerular deposition of C3c and C3d in IgA nephropathy

Background: Complement activation plays an important role in the pathogenesis of IgA nephropathy. The clinicopathological significance of the glomerular deposition of complement breakdown products, C3c and C3d in IgA nephropathy remains to be clarified. Methods: We examined the relationship between glomerular staining patterns of C3c and C3d and clinico-pathological findings with 163 patients with IgA nephropathy. Renal biopsy specimens were stained with C3c and C3d by immunofluorescence, and patients were divided into the following two groups: the intensity of C3c deposition stronger than C3d deposition, or equal to it (group A); the intensity of C3d deposition stronger than C3c deposition (group B). Results: In group A, the incidence of severe hematuria (over 20 urinary red blood cells in high-power field microscope (x400)) or of higher urinary fibrinogen degenerated products (over 0.1 mu g/ml) was significantly higher than that in group B. In addition, group A showed a significant decrease in the glomerular filtration rate. Group A also showed a significantly higher incidence of glomerular endocapillary proliferation than in group B. Conclusion: These findings suggest that the glomerular deposition of C3c is associated with the inflammatory active phase of glomeruli in IgA nephropathy. Copyright (C) 2000 S. Karger AG, Basel.