Complement

Question 1

Define complement

Answer 1

a group of plasma proteins that are activated by microbes and act in sequence to lyse pathogens and induce inflammation

Question 2

What are the 3 pathways through which complement can be activated?

Answer 2

alternative, classical, and lectin pathway

Question 3

What is the main feature of the complement system?

Answer 3

several C’ proteins are proteases that become activated only after cleavage

Question 4

Which complement proteins are not cleavage products?

Answer 4

C1q, C1r, and C1s form the C1 protein and are not cleavage products

Question 5

Define opsonisation

Answer 5

the process by which the pathogen is marked for ingestion and destruction by a phagocyte

Question 6

Describe the classical pathway

Answer 6

Ag-Ab complexes form, C1q,r,s form C1, C4 opsonises the pathogen, C2 activates C3 convertase & C5 (forms membrane attack complex)

Question 7

Describe the lectin pathway

Answer 7

Lectin binds to pathogen surfaces, activates C4 & C2, then C3 and C5 (membrane attack complex)

Question 8

Describe the alternative pathway

Answer 8

C3 binds directly to the pathogen surface, then activates C3 convertase and C5 (membrane attack complex)

Question 9

What is common to all three pathways?

Answer 9

the formation of the membrane attack complex trough C3 convertase and C5

Question 10

Which pathway links the innate and adaptive immune systems?

Answer 10

classical pathway

Question 11

Which Igs activate the classical pathway?

Answer 11

IgM in the staple form or IgG