3 main functions of the complement system

What is the main function of the complement system related to pathogen destruction?

It directly attacks pathogens by forming the membrane attack complex (MAC), which creates pores in the pathogen’s cell membrane, leading to cell lysis and death.

What is the role of the complement system in opsonization?

Complement proteins, like C3b, bind to pathogens, marking them for recognition and uptake by phagocytic cells (e.g., macrophages and neutrophils), enhancing pathogen clearance.

How does the complement system contribute to inflammation?

Complement activation generates peptides (e.g., C3a and C5a) that attract immune cells to the infection site and increase blood vessel permeability, promoting inflammation and immune response.

positive result

indicates complement fixation, meaning no hemolysis occurs because the complement was consumed by the antigen-antibody reaction.

negative result

shows hemolysis, where the red blood cells lyse due to the presence of free complement, which was not fixed by antigen-antibody complexes.