Significance of glomerular deposition of C3c and C3d in IgA nephropathy

Background: Complement activation plays an important role in the pathogenes is of IgA nephropathy. The clinicopathological significance of the glomerul ar deposition of complement breakdown products, C3c and C3d in IgA nephropa thy remains to be clarified. Methods: We examined the relationship between glomerular staining patterns of C3c and C3d and clinico-pathological findin gs with 163 patients with IgA nephropathy. Renal biopsy specimens were stai ned 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 stro nger than C3c deposition (group B). Results: In group A, the incidence of s evere hematuria (over 20 urinary red blood cells in high-power field micros cope (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 p roliferation than in group B. Conclusion: These findings suggest that the g lomerular deposition of C3c is associated with the inflammatory active phas e of glomeruli in IgA nephropathy. Copyright (C) 2000 S. Karger AG, Basel.