Diagnostic Status Of C4d Among Histopathological Spectrum Of Proliferative Glomerulonephritis

Abstract

Introduction: C4d is widely used as a marker for antibody-mediated rejection in renal transplant biopsies, but the significance of C4d deposition in various glomerulonephritis (GNs) in native renal biopsies is not fully elucidated yet. Native renal biopsy is a advantageous tool in establishing a diagnosis, treatment and prognosis of glomerular and tubulointerstitial diseases and  presence of C4d in native renal biopsies points towards activation of either classical or lectin pathway of complement fixation. Aim: To find the usefulness of C4d as a diagnostic tool in proliferative GN and to correlate C4d staining pattern with Immunoglobulins and complements on Immunofluorescence.  Materials and Method:  In this study, evaluation of  glomerular C4d staining by Immunohistochemistry in 100 native kidney biopsies of proliferative GN over a period of 2 years at a tertiary care centre was done. Result:  C4d staining was consistently present in cases of membranous nephropathy (n=24), IgA nephropathy (n=7), Lupus nephritis (n=23), Immune complex mediated GN (n=10), post infectious GN (n=7). One case each of membranoproliferative GN and IgM nephropathy were positive for C4d staining while negative staining was found in  one case each of Anti-glomerular basement membrane disease and ANCA negative pauci-immune crescentic GN.  41 % cases of C3 glomerulopathy (n=5) also showed negative C4d staining. Conclusion: C4d is helpful for evaluating renal biopsies and acts as a supportive adjunct in understanding the pathogenesis of GNs. C4d positivity can be used as a diagnostic tool in native renal diseases and also in transplant biopsies’ evaluation