C3 and amyloidosis: Amyloid plaques consist of not only pre-fibrillar and fibrillar forms of Aβ but also proteins such as apolipoprotein E (ApoE) (8, 9) and complement cascade components, such as complement component 1q (1q), cleaved parts of complement component 3 (C3), and complement component 5 (C5), as well as the terminal factors generating the membrane attack complex (MAC) (9, 10).