Figure 4.

Diagram depicting C5a as a prime mover at the center of an inflammatory amplification loop that mediates ANCA-induced vascular inflammation and nercrosis. Neutrophils activated by ANCA release factors that activate the alternative complement pathway, generating C5a. C5a is chemoattractant for neutrophils and primes neutrophils by C5aR engagement to display ANCA-antigens at the cell surface, which allows neutrophil activation by ANCA through FcR and Fab’2 binding. ANCA-activated neutrophils cause vascular necrosis and undergo leukocytoclasia.