Autoantibodies against complement C1q in acute post-streptococcal glomerulonephritis

Autoantibodies against complement C1q (anti-C1q) strongly correlate with the occurrence of severe lupus nephritis. Recent data suggest that anti-C1q might also correlate with more severe forms of acute post-streptococcal glomerulonephritis (APSGN). Therefore, we prospectively investigated the role of anti-C1q in 50 children with newly diagnosed APSGN. Associations between anti-C1q and disease manifestations as well as serum complement concentrations were analyzed. Nineteen of the 50 children (38%) with APSGN were positive for anti-C1q compared to 0/40 healthy controls. Levels of anti-C1q correlated negatively with serum C1q and C3 concentrations. Anti-C1q positive patients had significantly higher proteinuria and serum creatinine as well as more often oliguria, hypertension and delayed resolution of the disease than patients without anti-C1q. The data point to a potential pathogenic role of anti-C1q in APSGN. Determination of anti-C1q might help to identify patients at risk for prolonged courses of the disease.