Chapter 16.2: Complement Slides Flashcards
What is the complement system?
A system of enzymes and proteins that function in both the innate and adaptive branches that is part of the humoral immune response.
What connects the complement system to the function of the adaptive immune response?
The use of antibodies.
What does complement activation result in?
Lysis of the foreign cell.
What does the complement system indirectly trigger?
Inflammation and fever.
What are the three ways complement can be activated?
The classical pathway
The alternative pathway
The Lectin pathway
Which two pathways are part of the innate immune system?
The Alternative pathway
The Mannan-binding lectin (MBL) pathway
Which pathway is part of the adaptive immune system and why?
The Classical pathway because it is initiated by antigen-antibody complexes.
Where do all three pathways converge?
The point of a C3 convertase.
What is the classical pathway initiated by?
The binding of antibody to antigen.
What does the binding of the antibody cause?
Binding of IgM or IgG causes a conformational change in the Fc region of the immunoglobulin molecule.
What does the change of the Fc region allow for?
It allows for C1q to bind to the antibody which then undergoes a conformational change.
What does the conformation change to C1q cause?
Causes sequential binding and activation of the serine proteases C1r and C1s, which creates the C1qrs or C1s.
What does C1s do?
It rapidly cleaves C4 and C2 leading to the formation of C4b2a, also known as the C3 convertase.
What does the C3 convertase do?
Cleaves C3 leading to the formation of C4b2a3b complex which is the C5 convertase.
What does the insertion of C5b do?
Leads to the addition of the components C6, C7, and C8 (recruited and not cleaved) which forms an anchor for C9.
