Immunology Lecture - The Complement System

Flashcards on the complement system from an immunology lecture.

Complement System

A collection of circulating proteins that assist the innate immune system and enhance antimicrobial activity.

C3

The most abundant complement protein in the bloodstream, central to all complement pathways.

C3B

The active component of C3 that binds to pathogens and initiates further complement activation.

C3A

A chemoattractant component of C3 that promotes inflammation and recruits immune cells.

Opsonization

Coating of a pathogen with C3B to enhance phagocytosis by macrophages.

Membrane Attack Complex (MAC)

A complex formed in the late stages of complement activation that creates pores in pathogen membranes, leading to osmotic lysis.

C3 Tick Over

A constant, low-level breakdown of C3 in the blood, even without the presence of microbes.

Classical Complement Pathway

The first complement pathway to be discovered, activated by antibody binding to microbial surfaces.

CR1

Complement receptor type 1 found on phagocytes that binds to C3B, facilitating phagocytosis.

C1 Inhibitor (C1INH)

Soluble inhibitor that regulates the classical complement system by inhibiting the C1 complex.