Step-by-Step Process of The Complement System (The Complement System)

  • Pathogen recognition:

    • The immune system identifies a pathogen (invading organism).

    • Antibodies bind to antigens on the pathogen.

    • This allows C1 to attach and activate.

  • Activation of C2 and C4:

    • C1 causes C2 and C4 to split.

    • Fragments from C2 and C4 form C3 convertase.

  • C3 is cleaved:

    • C3 convertase splits C3 into C3a and C3b.