C3 and paroxysmal nocturnal hemoglobinuria: However, a significant number of patients with PNH who receive C5is, which control IVH, become susceptible to complement component 3 (C3)–mediated extravascular hemolysis (EVH) that occurs as C3 fragments increase the opsonization of PNH red blood cells, targeting them for phagocytosis in the liver and spleen [14,15].