Patterns of C4d staining in patients with lupus nephritis

Background: C4d, a cleavage product of the activated complement component C4, has attained considerable significance in the last few years for its role in helping elucidate the pathophysiology of renal allograft rejection.This investigation attempts to study the patterns of C4d deposition in native kidneys of patients with lupus nephritis. Methods: Renal biopsies from 16 patients with lupus nephritis were reviewed for C4d deposition in the glomeruli and peritubular capillaries. Renal involvement in these patients was classified histopathologically according to World Health Organization classification as class II (4 cases), class III (3 cases), class IV (8 cases), and class V (1 case). Results: All 16 patients (100%) showed deposition of C4d in the glomerular structures, and one also had focal deposition of C4d in the peritubular capillaries. Conclusion: In 2 previous studies that reported C4d staining characteristics in a total of 28 patients with lupus nephritis, all patients had C4d deposition in the glomeruli, and none had C4d staining in the peritubular capillaries. Although the findings of the current study confirm those of previous studies with regard to glomerular C4d deposition, the additional focal deposition of C4d in the peritubular capillaries (a marker of humorally mediated allograft rejection) in 1 patient is interesting.