Complement System Activation and Disease Severity in Patients with Lupus Nephritis in Lagos

Lupus nephritis is one of the most severe manifestations of systemic lupus erythematosus, and complement system dysregulation plays a central role in its pathogenesis and perpetuation. This study evaluates complement system activation markers, specifically serum C3, C4, CH50, and soluble C5b-9, in patients with lupus nephritis stratified by renal biopsy class at a rheumatology unit in Lagos, South West Nigeria. A cross-sectional analytical design was adopted, recruiting 80 patients with biopsy-confirmed lupus nephritis and 40 SLE patients without renal involvement as comparators. Complement components were measured by immunonephelometry and ELISA. Anti-dsDNA antibody titre, urinary protein-to-creatinine ratio, serum creatinine, and complete blood count were simultaneously obtained. The International Society of Nephrology/Renal Pathology Society classification from biopsy reports was used to stratify disease. Multivariate logistic regression identified complement markers most strongly associated with proliferative nephritis classes. The study also evaluates the utility of complement markers as treatment response surrogates in follow-up. Findings will advance the biochemical understanding of lupus nephritis in West African women and contribute to locally applicable monitoring protocols. Keywords: lupus nephritis, complement system, C3, C4, systemic lupus erythematosus, Lagos.