4: Complement System

Question 1

In what 3 ways does the complement system eliminate bacteria?

Answer 1

1. promotes a localized inflammatory response
2. assists immune cells in phagocytosis
3. damages bacterial cell membrane

Question 2

3 pathways of the complement system

Answer 2

1. classical
2. MBLectin
3. alternative

Question 3

What enzyme do all the complement pathways converge at?

Answer 3

C3 convertase

Question 4

3 proteins used in classical pathway

Answer 4

C1, C4, C2

Question 5

3 proteins used in MBLectin pathways

Answer 5

MASP, C4, C2

Question 6

3 proteins used in alternative pathway

Answer 6

C3b, factor B, factor D

Question 7

What are C3a and C5a known as?

Answer 7

anaphylatoxins

Question 8

What binds to create C5 convertase?

Answer 8

C3 convertase and C3b

Question 9

Are the proteins in the complement system soluble or insoluble?

Answer 9

soluble

Question 10

Where are the complement proteins synthesized?

Answer 10

liver

Question 11

How is the classical pathway activated?

Answer 11

IgG or IgM antibodies binding to surface

Question 12

How is the alternative pathway activated?

Answer 12

spontaneous activation in the blood or bacterial surfaces

Question 13

How is the lectin pathway activated?

Answer 13

opsonins binding to bacterial cell surface

Question 14

Which 2 proteins are the points of amplification?

Answer 14

C3 and C5

Question 15

MBL

Answer 15

mannose binding lectin binds to mannose residues and other sugars on pathogens

Question 16

What are the 2 serum proteins that can bind to bacterial surfaces to initiate the lectin pathway?

Answer 16

MBL and ficolins

Question 17

Ficolins

Answer 17

binds to carbohydrate structures on bacterial and fungal cells to activate the lectin pathway

Question 18

What is the C3 convertase in the alternative pathway?

Answer 18

C3bBb

Question 19

What is the C3 convertase in the classical and lectin pathways?

Answer 19

C4b2a

Question 20

What does C5b initiate formation of?

Answer 20

the membrane attack complex

Question 21

What is the outcome of the membrane attack complex?

Answer 21

lysis of the cell

Question 22

What type of bacteria is more resistant to the membrane attack complex?

Answer 22

gram-positive

Question 23

Opsonization

Answer 23

a process which uses host proteins to tag particles such as bacteria for elimination by phagocytes

Question 24

What are the 3 main complement receptors?

Answer 24

CR1, CR3, CR4

Question 25

What are the results of anaphylatoxins?

Answer 25

1. leakage of antibodies into the site of immune challenge
2. migration of innate immune cells into inflammatory lesions
3. activation of phagocytes entering the lesion

Question 26

T/F: Complement proteins are antigen-specific

Answer 26

F

Question 27

Regulatory proteins

Answer 27

protect host cells from complement-mediated damage secondary to inflammation

Question 28

What are the 3 main regulatory proteins?

Answer 28

C1 inhibitor, decay-accelerating factor, and protecin

Question 29

BLAD

Answer 29

bovine leukocyte adhesion deficiency