Comparative Analysis of C4d Deposition with The Severity, Laboratory Results and Histopathologic Scores in Lupus Nephritis

Background: Lupus nephritis (LN) is a serious complication of systemic lupus erythematosus (SLE) and evident in 60% of patients. Complement system and its product, complement component 4 degradation (C4d), plays an important role in the pathogenesis of LN. The aim is to determine the prognostic value of C4d detection in different classes of LN and correlation with laboratory results and histopathologic activity score. Methods: Thirty-five patients with LN were collected between January to September 2023. Blood levels of anti-nuclear antigens (ANA), anti-double stranded DNA antibody (Anti-dsDNA), C3, C4, and 24hr urine protein were measured. Renal tissue biopsy was examined regarding glomerular C4d antibody immunohistochemical staining and Classes of LN according to International society of nephrology/Renal Pathology Society (ISN/RPS). Results: Glomerular C4d was expressed in 40% of LN patients and was significantly correlated with urinary protein excretion (p=0.001) and Anti-dsDNA antibody (P=0.048), but not with LN classes or activity score or low complements. Conclusions: Glomerular C4d deposition of LN does not indicate the present disease activity but may help to identify a subset of patients with worse renal prognosis, providing insights about the therapeutic approaches for SLE with LN. Keywords: Lupus nephriti, glomerular C4d, proteinuria, Anti-double stranded DNA Antibody.