Immunology Unit 9: Complement System

These flashcards cover key concepts related to the complement system in immunology, including pathways, components, functions, and implications of deficiencies.

What is the function of the complement system?

A system of blood proteins that helps antibodies and immune cells clear pathogens through lysis, opsonization, and inflammation.

What activates the classic complement pathway?

Antigen-antibody complexes, mainly involving IgG or IgM.

What is the role of the Recognition Unit in the classic pathway?

It recognizes and binds to the antibody attached to the antigen.

Which components are involved in the Activation Unit of the complement system?

C4, C2, and C3.

What is the final step of the complement system called?

Membrane Attack Unit, which forms the Membrane Attack Complex (MAC).

What is the difference between the classic and alternative pathways of complement activation?

The classic pathway is activated by antibody-antigen complexes, while the alternative pathway is activated directly by pathogen surfaces.

What substances can inactivate complement activity?

C1-inhibitor, Factor I, Factor H, and S protein.

What are the consequences of complement deficiencies in C1, C4, or C2?

They can lead to autoimmune diseases, such as Lupus.

What is required to reactivate inactivated complement?

Fresh serum is required; it cannot be reactivated once inactivated.

What is bacteriolysis?

The destruction of bacterial cells through the action of complement and antibodies.