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Basic Immunology- Module 1 > Complement > Flashcards

Flashcards in Complement Deck (85)
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1

What are the main effector functions in complements role in killing of microbes?

opsonisation; leukocyte activation and cell lysis

2

What complement factor is involved in the activation of leukocytes?

C5a

3

What are the functions of complement?

killing of microbes; briding innate and adaptive immunity; immune complex processing; removal of apoptotic cells

4

What are the functions of C5a?

potent anaphylatoxin; chemotaxis; endothelial activation; prothormbotic

5

What are the functions of C5b-9?

cell lysis; platelet activation; endothelial activation; prothrombotic

6

How is the classical pathway of complement activated?

by binding of C1q to Fc portions of IgG and IgM or recognises microbial surface directly

7

How is the lectin pathway of complement activated?

mannose binding lectin and ficolins interacting with bacterial carbohydrate residues

8

How is the alternative pathway of complement activated?

spontaneously

9

What is a zymogen?

inactive pro-enzyme which become activated after proteolytic cleavage

10

What associates with MBL and ficolins to trigger cleavage of complement?

MBL-associated serine proteases (MASPs)

11

What is C1 comprised of?

recognition protein C1q assocated with proteases C1s and C1s

12

What do all 3 complement pathways generate?

C3 convertase

13

What is C3 convertase?

a multisubunit protein with protease activity that cleaves complement component 3 (different types depending by pathway)

14

what is the main effector molecules of the complemetn system?

C3b

15

Where does C3 convertase cleave C3?

when it is bound covalently to the pathogen surface releasing C3a while leaving lots of C3b bound to the surface

16

What is the function of C3a?

binds to specific receptors and helps induce inflammation

17

What is C3b degraded into?

C3f and C3dg

18

How does covalent bond formation between C3b and the pathogen surface take palce?

due to highly reactive thioester bond hidden inside the folded C3 protein

19

What are the components of C3 convertase in the lectin and classical pathways?

C4b2a

20

What are the compoents of C3 convertase in the alternative pathway?

C3bBb

21

What is the difference in glycans between yeast and vetebrates?

yeast glycans terminate in mannose resudes rather than sialic acid residues

22

Where is MBL synthesised?

liver

23

What is a collectin?

protein that has an amino-terminal collagen-like domain and a carboxy-terminal C-type lectin domain

24

What is the difference in structure between ficolins and MBL?

ficolins have a fibrinogen-like domain rather than lectin domain

25

How many types of ficolin do humans have?

L-ficolin (2); M-ficolin (1) and H-ficolin (3)

26

Where are the ficolins produced?

L and M ficolins are produced by the liver; M-ficolin is procued by lung and blood cells

27

What happens when MBL bound to MASP 1,2 and 3 binds to a pathogen surface?

MASP-1 is conformationally changed and activates MASP-2 which can cleave C4 and C2

28

What happens to C4 once activated by MASP-2?

similarly to C3, C4b has a reactive thioester which binds to pathogen surface

29

What happens to C2 once activated by MASP-2?

C2a remains bound to C4b

30

What is the function of C4bC2a?

cleaves many molecules of C3 into C3b and C3a