Complement system Figure 7: Overview of the complement system Alternative pathway Lectin pathway Classical pathway spontaneous activation mannose binding antibody binding C3 C3b MBL MASP. C1q/r2/s2 Factor D B Bb MASP-2 C4/C2-+C4b/C2b C4/C2-+C4b/C2b C3b/Bb C4b/C2b C4b/C2b C3 convertase C3a +C3b C5 convertase anaphylatoxin opsonization lytic pathway inflammation omation of membrane phagocytosis attack comlex lysis of pathogens C4a C3a C5a C5b,c6,C7,c8,c9 (adapted from Janeway 2001)Complement system