Hunter-Complement

Question 1

Who came up with the term complement?

Answer 1

Jules Bordet

studying cholera

Question 2

What is complement?

Answer 2

> 30 constitutively expressed serum & cell surface proteins
help with innate immune response
helps antibodies in adaptive humoral immune response
helps eliminate immune complexes

Question 3

What would complement deficiencies do?

Answer 3

increase susceptibility to pyogenic bacteria

precipitate immune complex diseases

Question 4

Complement shares features with which 2 pathways?

Answer 4

the coagulation & kinin pathways

Question 5

What are zymogens?

Answer 5

substrate proteins (proenzymes) are cleaved and acquire proteolytic activity
amplification, one protease cleaves a protein to activate it. etc.
zymogens are the inactive form

Question 6

What are the 4 major fcns of complement?

Answer 6

1. opsonization (binding to promote phagocytosis)
2. inflammation, chemotaxis, activation of immune cells
3. clearance of immune complexes
4. form pores in pathogen membranes–death

Question 7

T/F 50% of all bacteria can be destroyed via the pore-forming function of complement.

Answer 7

FALSE. ONly like 2 bacteria in a trillion can be killed this way. Even though it is cool.

Question 8

What are immune complexes?

Answer 8

antigen-antibody bound

Question 9

What part of a pathogen does the complement respond to in the classical pathway?

Answer 9

antigen antibody complex

Question 10

Which parts of the complement start the classical pathway by doing their thing & recognizing stuff?

Answer 10

C1q, r, s complex
C4
C2
**then we get to the C3 convertase

Question 11

Which parts of the pathogen start the lectin pathway by being recognized by the complement?

Answer 11

mannose-binding lectin or ficolin binds carbs on pathogen surfaces

Question 12

Which parts of the complement do the recognizing of the pathogen in the lectin pathway?

Answer 12

MBL/ficolin, MASP-2
C4
C2
**then we get to the C3 convertase

Question 13

Which part of the pathogen is recognized by the complement in the alternative pathway?

Answer 13

pathogen surfaces

Question 14

Which part of the complement does the recognizing in the alternative pathway?

Answer 14

C3
B
D
**then we get to C3 convertase

Question 15

After we get to C3 convertase…what kinds of by-products do we get?

Answer 15

C3a, C3b, C5a

Question 16

What is the effect of C3a & C5a being produced?

Answer 16

peptide mediators of inflammation

phagocyte recruitment

Question 17

What is the effect of C3b?

Answer 17

binds to complement receptors on phagocytes
opsonization of pathogens
removal of immune complexes

Question 18

What are the terminal complement components that you can get after you get C3b? What do these terminal components cause?

Answer 18

C5b
C6
C7
C8
C9
**membrane-attack complex, lysis of certain pathogens & cells

Question 19

Typically, in the complement system what does a capital letter identify? What does a lower case letter identify?

Answer 19

Capital Letter: complement protein

Lower Case Letter: cleavage fragment (except for r & s)

Question 20

What is the order of activation in the classical pathway?

Answer 20

C1, C4, C2, C3, C5-9

Question 21

Which indicates the smaller fragment & which the larger fragment: a & b? What is the exception to this rule?

Answer 21

a is small.
b is large.
Exception: C2b is the small fragment.

Question 22

What does the letter i before a protein indicate?

Answer 22

the enzymatically inactive form

Question 23

Which parts of the complement fit this description? binding to antigen-antibody complexes and pathogen surfaces

Answer 23

C1q

Question 24

Which parts of the complement fit this description? binding to carb structures such as mannose or GlcNAc on microbial surfaces

Answer 24

MBL
Fincolins
C1q
Properidin
factor P

Question 25

Which parts of the complement fit this description? Activating enzymes

Answer 25

``` C1r C1s C2a D MASP-2 ```

Question 26

Which parts of the complement fit this description? Membrane-binding proteins & opsonins

Answer 26

C4b & C3b

Question 27

Which parts of the complement fit this description? Peptide mediators of inflammation

Answer 27

C5a, C3a, C4a

Question 28

Which parts of the complement fit this description? membrane-attack proteins

Answer 28

``` C5b C6 C7 C8 C9 ```

Question 29

Which parts of the complement fit this description? complement receptors

Answer 29

``` CR1 CR2 CR3 CR4 CRIg ```

Question 30

Which parts of the complement fit this description? Complement-regulatory proteins

Answer 30

``` C1NH C4BP CR1 MCP DAF H I P CD59 ```

Question 31

Describe the structure of the C1 complex.

Answer 31

``` C1q is the collagen region C1r & C1s is also there. looks like a tulip detects bacteria as a unit. complexes for the other pathways look similarly ```

Question 32

What are all of the things that C1q recognizes?

Answer 32

pattern recognition receptor bacterial porins & LPS IgM, IgG, C-reactive protein

Question 33

Describe the classical pathway in more detail.

Answer 33

C1 complex comes together & the C1s becomes active (serine protease). It cleaves C4 into a &b. C4b binds to pathogen surface or is hydrolyzed. Enzyme cleaves C2. C2a stays on pathogen surface w/ C4b. C4b2a=C3 convertase. Cleaves C3 into C3a & b. C3b stays.

Question 34

What happens to C4b or C3b if they don't stick to the pathogen surface right away?

Answer 34

They are hydrolyzed!!! Water is added to the bond.

Question 35

What is the effect of having iC3b on a bacterial surface?

Answer 35

it opsonizes it for destruction via phagocytosis. CR3 on macrophages, neutrophils, and dendritic cells attaches to iC3b--endocytosis & phagocytosis!