Final answer:
The three stages of complement activation are initiation, amplification and cascade, and membrane attack complex formation.
Step-by-step explanation:
The three stages of complement activation are:
- Initiation: This stage is triggered by the presence of an antigen-antibody complex in the classical pathway or by acute-phase proteins binding to a pathogen in the lectin pathway. It involves the binding of complement proteins to the pathogen surface.
- Amplification and cascade: Once initiated, the complement activation cascade is rapidly amplified by the enzymatic activation of complement proteins, leading to the production of larger numbers of active complement components.
- Membrane attack complex formation: The final stage involves the formation of the membrane attack complex (MAC), which is composed of complement proteins C5-C9. The MAC creates pores in the pathogen's membrane, leading to cell lysis and destruction.