Immunology-9 (Kyle)

Question 1

What is the classical pathway for complement activation?

Answer 1

Antigen : Ab complexes (First to act)

Question 2

What is the lectin pathway of complement activation?

Answer 2

Lectin binding to pathogen surfaces (Second to act)

Question 3

What is the alternative pathway of complement activation?

Answer 3

Pathogen surfaces. (Third to Act)

Question 4

What is the common theme of complement activation?

Answer 4

Clevage of C3 to C3a and C3b. C3b will be covalently bound to surface components of pathogen.

Question 5

What does the clevage of C3 do to the pathogens?

Answer 5

Recrutes inflammatory cells,

Question 6

What does the complement cascade do?

Answer 6

Marks pathogens for destruction by phagocytes ( Opsonization )

Question 7

What are anaphylatoxins?

Answer 7

Inflammatory mediators rpoduced by the complement cascade.

Question 8

What do anaphylatoxins actually do ?

Answer 8

These small molecules are chemotactic and induce vascular permeability which induces inflammatory responses.

Question 9

Where are components of the complement cascade produced?

Answer 9

In the liver in their inactive form.

Question 10

What do anaphylatoxins do?

Answer 10

Recruit fluid and immune cells to sites of antigen deposition.

Question 11

What is the most important product of the complement cascade?

Answer 11

Deposition of the opsonin C3b

Question 12

Why is C3b important?

Answer 12

Complement receptors on phagocytes bind to C3b (and fragments of C3b) which facilitates uptake and destruction of the pathogen

Question 13

What enzyme is C3b a part of that activates the membrane attack complex?

Answer 13

Convertase enzyme

Question 14

What does C3a do ?

Answer 14

Recrutes phagocytes

Question 15

Is the alternative pathway of activation a purely innate mechanism?

Answer 15

Yes

Question 16

What is the race of C3 cleavage?

Answer 16

Very low but in the presence of bacteria the rate will be greatly increased.

Question 17

What happens after C3b is deposited on the surface of a bacterium?

Answer 17

It becomes a ligand for factor B. When factor B binds to C3b, factor D cleaves factor B.

Question 18

When factor D cleaves factor B what is the end result?

Answer 18

C3b, Bb, and Ba are produced.

Question 19

What happens when C3b binds to C3b, Bb ?

Answer 19

C5 convertase is produced.

Question 20

What binds to C5b?

Answer 20

C6, C7, C8, and tons of C9. This attack complex forms a pore in the bacterial membrane.

Question 21

What complement component is a main part of the lectin pathway of complement activation?

Answer 21

MBP (mannose- binding proteins)

Question 22

What does MBP do ?

Answer 22

MBPbinds to the terminal mannose residues on the surface of the bacteria. The glycoproteins and glycolipidsthat hae mannose residues which are unique to the bacteria and not the host.

Question 23

Once bound to the microbial surface what does MBP have a high affinity for ?

Answer 23

MASP-1 and MASP-2 which activates them.

Question 24

What happens when MASP-1 and MASP-2 are activated?

Answer 24

They are able to cleave C4 to form C4a and C4b. And cleave C2 to C2a and C2b.

Question 25

What happens when C2b and C4b bind to the pathogen surface?

Answer 25

Together they for the active C3 convertase which cleaves C3 to C3a and C3b. **After this step the cascade is identical to the classical pathway

Question 26

What is the end result of the classical pathway of complement activation?

Answer 26

Implantation of C3b onto the bacterial cell membrane.

Question 27

What are the components of the classical C3 convertase ? What binds to the classical convertase?

Answer 27

C2a and C4b. C3, which is ceaved to C3a and C3b. C3b implants in the pathogen surface.

Question 28

What is the purpose of the C5b, C6, C7, C8 complex do ?

Answer 28

Recrute tols of C9 which physically form the pore

Question 29

What is the most important end result of complement activation ?

Answer 29

C3b deposition.

Question 30

What does C3b deposition do ?

Answer 30

In the Classical and Lectin pathways will still be activated but the alternative pathway will amplify the response. The Pathogen will be opsonized.

Question 31

For people who cant make an activated membrane complex, what pathogen is a big problem ?

Answer 31

Niceria

Question 32

What is the mechanism of innate activation of the classical pathway?

Answer 32

C1 binds to C-reactive protein and IgM. This complex bonds to phosphocholine which is on the surface of the pathogen.

Question 33

Why is opsonization via complement important?

Answer 33

Look this up

Question 34

Is deposition of C3b permanent?

Answer 34

Yes, Once compement has been deposited it is there forever and is a permanent marker for destruction.

Question 35

Is C1q always activated?

Answer 35

There is always some level of activation but it is not always fully activated.

Question 36

What does C1inhibitor do? (C1INH)

Answer 36

C1INH binds to activated C1r : C1r forcing the dissociation from C1q

Question 37

What happens when C1INH is deficient?

Answer 37

C1INH deficiency causes a serious illness that is characterized by systemic edema.

Question 38

What is the systemic edema from in (C1INH) deficiency?

Answer 38

Overproduction of anaphylatoxins. Results in hereditary angioneurotic edema (HANE) which is treated by C1INH replacement therapy.

Question 39

What does CD59 do?

Answer 39

Binds to C5b