Chapter 3

Question 1

complement system

Answer 1

cascade of proteolytic cleavage reactions
tag pathogens of phagocytosis and directly kill pathogens by creating holes in their membranes (MAC)

Question 2

complement activation

Answer 2

activation of the complement system

Question 3

C3 convertase enzyme

Answer 3

cleaves C3 into C3a and C3b

Question 4

C3a

Answer 4

acts as anaphylatoxin to induce inflammation, recruit phagocytes and induce degranulation

Question 5

C3b

Answer 5

covalently attaches to pathogen surface to induce phagocytosis

Question 6

alternative pathway

Answer 6

spontaneous, already initiated and ready to go whenever pathogen enters body

Question 7

lectin pathway

Answer 7

activated by recognition of bacterial oligosaccharides ending in mannose, fucose

Question 8

classical pathway

Answer 8

best activated by antibodies bound to pathogen surface

Question 9

iC3

Answer 9

binds factor B, cleaved by factor D forming Ba and Bb fragments giving iC3bBb

Question 10

iC3Bb

Answer 10

cleaves C3 to form C3a and C3b which attaches to pathogen surface

Question 11

alternative pathway C3 convertase C3bBb

Answer 11

cleaves more C3 to form C3b that covalently attaches to pathogen surface to react with factor B and factor D to form more alternative C3 convertase
a nonspecific positive feedback loop

Question 12

properdin (factor P)

Answer 12

accelerator
stabilizes C3bBb on pathogen cell surfaces

Question 13

factor H

Answer 13

brake
binds C3b and promotes cleavage of C3b by factor I to form inactive iC3b

Question 14

decay accelerating factor (DAF)

Answer 14

inactivates C3bBb by promoting dissociation of Bb from C3b

Question 15

membrane cofactor protein (MCP)

Answer 15

binds C3bBb and promotes dissociation of Bb and cleavage of remaining C3b by factor I to form inactive iC3b

Question 16

complement receptor CR1

Answer 16

on macrophages
binds C3b
stimulates phagocytosis

Question 17

complement receptors CR3 and CR4

Answer 17

binds iC3b
on macrophages
stimulate phagocytosis

Question 18

alternative C5 convertase

Answer 18

formed by C3bBb recruiting another molecule of C3b to form C3b2Bb
cleaves C5 to C5a and C5b`

Question 19

C5b

Answer 19

associates with C6 and C7
exposed hydrophobic region of C7 allows association of C5b67 with pathogen membrane

Question 20

C3a and C5a

Answer 20

provoke inflammation
increase vascular permeability
induce granulation of mast cells and permeability
act as a chemoattractant for phagocytes
increase expression of complement receptors

Question 21

mannose binding lectin (MBL)

Answer 21

binds to mannose on pathogen cell surfaces
complexed with proteases MASP1 and MASP2

Question 22

C-reactive protein

Answer 22

binds to phosphocholine on pathogen cell surfaces

Question 23

Opsonins

Answer 23

MBL and C-reactive proteins
monocytes and macrophages have receptors for each

Question 24

classical C3 convertase, C2b4b

Answer 24

MBL binding activates associated MASP1 and MASP2
C1q binding to C-reactive protein or immunoglobulin complexes activates associated C1r and C1s
cleaves C4 and C2 to form C2b4b

Question 25

blood coagulation system

Answer 25

minimizes blood loss hinders entry of pathogens into circulation platelets release prostaglandin bradykinin causes vasodilation

Question 26

alpha2 macroglobulin

Answer 26

cages protease attack exposes internal thioester that bonds with protease then undergoes shape change to enclose protease and prevent access of other substrates

Question 27

defensins

Answer 27

alpha made by neutrophils beta made by various epithelial

Question 28

abnormal clearance of gram + bacteria

Answer 28

PAMPs masked from PRRs of innate immune cells opsonization to complement facilitates clearance by phagocytes

Question 29

Which is ONLY active in the classical complement cascade?

Answer 29

C1

Question 30

Which complement protein forms the pore in the membrane attack complex?

Answer 30

C9

Question 31

What is the main opsin in the complement cascade?

Answer 31

C3b

Question 32

Which complement cascade involves the action of MASPs?

Answer 32

alternative

Question 33

Which is the C3 convertase of the alternative cascade?

Answer 33

C3bBbP

Question 34

Which of the complement cascades acts the fastest?

Answer 34

alternative

Question 35

What is the main anaphylatoxin produced in the complement cascade?

Answer 35

C5a

Question 36

What is the function of properdin?

Answer 36

Stabilize C3 convertase

Question 37

What is the function of DAF?

Answer 37

Degrade C3 convertase