Final answer:
Complement proteins are soluble proteins that help destroy extracellular pathogens by serving as markers, opening pores in microbial cell membranes, and causing the bacteria's destruction. Complement proteins have other roles in the immune response, including opsonization, inflammation, and immune clearance.
Step-by-step explanation:
Complement proteins are a group of soluble proteins that function in the immune response to destroy extracellular pathogens. They serve as markers to indicate the presence of a pathogen to phagocytic cells and enhance engulfment, a process called opsonization. Certain complement proteins can combine to open pores in microbial cell membranes, resulting in bacterial lysis. These pores cause the pathogen's contents to leak and lead to its destruction.
Complement proteins are part of a cascade of sequential binding events that coat the pathogen in complement proteins. This cascade is activated in the presence of invading microbes.
Aside from causing bacterial lysis, complement proteins have other roles in the immune response, including:
- Opsonization: Marking pathogens for phagocytosis.
- Inflammation: Attracting immune cells to the site of infection.
- Immune clearance: Removing pathogens through complement-mediated effector mechanisms.