Increased renal damage in hypocomplementemic patients with ANCA-associated vasculitis: retrospective cohort study.

There is an association between low complement and the degree of renal damage in patients with AAV. Patients with renal biopsies confirming IC and/or complement deposits showed more aggressive renal disease. Key Points • The complement system has an important role in the pathogenesis of vasculitis associated to antineutrophilic cytoplasmic antibody. • The studies in murine models confirming the complement activation by alternative pathway and particularly the receptor C5a (C5aR) is necessary for the development of glomerulonefritis. • Complement deposit observed in the renal biopsies of patients diagnosed with AAV was correlated to greater kidney damage, greater proteinuria and major disease activity compared to patients diagnosed with typical pauci-immune vasculitis. • The presence of hypocomplementemia at the onset of the disease was also associated with a greater organ involvement, poor prognosis and greater mortality.