Complement System

Question 1

classical pathway trigger

Answer 1

fixation of C1 to antibody (IgM or IgG) that has combined with an antigen

Question 2

alternative pathway trigger

Answer 2

triggered by microbial surface molecules (endotoxin or LPS), complex polysaccharides, and other substances - does not reuire an antibody

Question 3

lectin pathway trigger

Answer 3

plasma mannose-binding lectin binds to carbohydrates on microbes and directly activates C1

Question 4

3 main functions of complement system

Answer 4

production of fragments that stimulate inflammation (C5a)

opsonization (via production of C3b)

Cell lysis (via formation of MAC complex on cell membrane of invader)