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Complement Systems - Coggle Diagram

- - - - Igs bind and activate C1: IgM > IgG3 > IgG1 >> IgG2
  - - - C4a remains in the fluid while C4b binds to the surface of the pathogen
        
        C4b binds to C2, which is cleaved by C1s
        
        C2 generates C2b and C2a
        
        C2a binds to C4b to form C4b2a also known as classical pathway C3 convertase
        
        lectin and classical pathways converge
        
        Factor I cleaves C4b on the surface after C2a has been displaced
- - - - Factor B binds to C3b to form C3bB
        
        Factor D then cleaves Factor B in the cell surface-associated C3bB complex
        
        Ba (in the fluid) and Bb (remains attached to C3b) are generated
        
        C3bBb = alternate pathway C3 convertase
        
        Cleaves C3 into C3a and C3b
        
        stabilized by factor P
        
        When Factor H binds to C3b - the pathway stops
- - - - Microbes: Gram-positive, Gram-negative, fungi or yeast
      - MBL and ficolin are found in the circulation complexed with proteases known as mannose-associated serine proteases = MASPs
        
        MASP 2 cleaves C4 and C2 to form C4b2a
      - homologous to C1q in classical pathway
- - - - anaphylatoxin: molecule that induces potent inflammatory responses by activating multiple cells
      - opsonin: its deposition on the pathogen surfaces enhances pathogen uptake by phagocytic cells
      - C3b binds to the pathogen surface - the next component in the sequence is C5
        
        C5 is cleaved into C5b
        
        C5b deposits on the surface of the pathogen, allowing the binding of components C6, C7, C8, C9
        
        and C5a
        
        Form the MAC = Membrane Attack Complex that lead to the lysis of a pathogen
      - C3 convertase with C3b bound = C5 convertases
        
        C42a3b in classical and lectin pathways
        
        C3bBb3b in alternative pathway