Structure And Function Of Complement System

Question 1

Structures that does Lysis require?

Answer 1

Ab— heat insensitive
Complement— heat sensitive

Question 2

3 functions of complement system

Answer 2

1-Opsonization and phagocytosis
2-Complment-mediated cytolysis
3-Stimulation of inflammatory reactions

Question 3

Which structures binds to microbe in order to opsonize

Answer 3

C3b
C4b

Question 4

The ab-microbe + C3b complex is recognized by which receptor

Answer 4

CR1

Question 5

Which formation occur in the Complement mediated cytolysis stage

Answer 5

MAC

Question 6

How is the most circulating forms of complements

Answer 6

Inactive —> proenzymes or zymogens

Question 7

Complement proteins synthesized in

Answer 7

Hepatocytes mostly
Tissue macrophages
Blood monocytes
Epi cells

Question 8

Which cytokines induce the secretion of certain complement proteins

Answer 8

Acute phase proteins
TNF
IL-1
IL-6
IFN-y

Question 9

3 activation of complement cascades

Answer 9

Alternative — no need for ab
Classical — ab
Lectin — Mannose

Question 10

Activation of C3

Answer 10

C3 activation occurs by the cleavage of C3 to C3b and C3a
C3b for opsonization
C3a for inflammation

Question 11

Alternative pathway is a part of the which immune system

Answer 11

Innate immune system

Question 12

Formation of MAC

Answer 12

Initiated by C5 conversion to C5a and C5b
C5b binds C6
After then C7,C8,C9 binds and forms MAC

Question 13

Initiation of Classical pathway dependent on

Answer 13

ab-ag interaction

Question 14

Classical pathway is a part of which immune system

Answer 14

Adaptive immune system

Question 15

Classical pathway ag-ab interaction causes

Answer 15

Activation of C1
For activation two heads of C1q must be simultaneously bound to the Fc region of IgG

Question 16

Which abs in Classical pathway can bind C1

Answer 16

Abs that have bound to ag
IgM
IgG

Question 17

Which type of Igs mostly activate the complement system at very high amounts

Answer 17

IgG1
IgG3

Question 18

Which Ig type can not activate the complement system

Answer 18

IgG4

Question 19

Lectin pathway is dependent of

Answer 19

Mannose binding lectin

Question 20

Role of Vitronectin

Answer 20

Inhibits the lysis by prevents the binding of C9 to MAC

Question 21

Roles of complement system

Answer 21

Cell lysis— MAC
Trigger inflammation- C3a, C5a
Attract phagocytes— C5a,C3b
Opsonise ag —C3b
Remove immune complexes—C3b
Activate naive B lymphocytes —C3b

Question 22

Role of complement system in the Anaphylatoxins and inflammatory response

Answer 22

Binding of anaphylatoxins to G-protein coupled receptors stimulates the release of pro inflammatory mediators from cells
*C3a and C5a

Question 23

Role of complement system in clearance of circulating immune complexes

Answer 23

Complement receptor of erythrocyte recognizes C3b by Fc
Bring it to Liver
Turn back to circulation
And phagocytosis occurs
Erythrocyte acts as a carrier

Question 24

Tremendous amplification of anti-pathogen response due to

Answer 24

Formation of C3b

Question 25

Complement activation promotes Clearance of pathogens and their products by

Answer 25

Opsonization
Immune complex clearance
Enhancement of ag presentation
Enhancement of B cell activation, memory and the generation of chemoattractant