Complement activation pathways Antigen-antibody complexes Microbial surfaces Microbial surfaces Classical pathway Mannanbinding lectir Alternativepathway pathway C1q MBL c3 C1r-C1s MASP1-MASP2 B C4 C4 0 c2 C2 C3 Opsonic fragments, Vasoactive and chemotactic C3b,ic3b cs fragments,C4a,C3a,C5a C6 C7 Immune response stimulating fragments, C3d 9 Membrane-attack complex (MAC) Complement activation pathways