18. Complement Flashcards Preview

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Flashcards in 18. Complement Deck (25):
1

Complement is produced by ... / play role in ... (generally)

liver
role in innate immunity and inflammation

2

Membrane attach complex (MAC) defends against

Gram (-) bacteria

3

Complement activation - pathways (generally mediated by)

1. classic pathway - IgG or IgM mediated42microbe surface molecules and spontaneous
3. lecithin pathway - mannose or other sugars on microbe surface

4

Complement function

1. opsonization
2. Anaphylaxis
3 Neutrophil chemotaxis
4Cytolisis by MAC
5. helps clear by MAC :

5

Complement types
1. opsonization
2. Anaphylaxis
3 Neutrophil chemotaxis
4Cytolisis by MAC
5. helps clear by MAC :

1. opsonization C3b
2. Anaphylaxis C3a, C4a, C5a
3 Neutrophil chemotaxis C5a
4Cytolisis by MAC: C5b-9
5. helps clear immune complex :c3b

6

primary opsonins in bacterial defence

1. C3b
2. IgH

7

Beside phagocytosis enhancement , C3b also help

clear immune complexes (C3b- tagged immune complex is destroyed)

8

Complement inhibitors

1. Decay accelaratin facto
2C1 esterase inhibitor help prevent complement activation on self cells (eg. RBCs)

9

Decay accelarating factor is aka

CD55

10

complement activation - alternative pathway

.

11

complement activation - classic pathway

.

12

.complement activation - lecithin pathway

.

13

C2 historically

the larger fragment of C2 was called C2a but is now refereed to as C2b

14


• What is the complement system?

A system of interacting plasma proteins that plays a role in innate immunity and inflammation.

15

Against what type of bacteria does the membrane attack complex defend?


Gram-negative bacteria, especially Neisseria strains

16


• In the complement system, what is the function of the plasma protein C3b?


Opsonization (C3b binds bacteria)

17

• In the complement system, proteins ____, ___ and ____ can cause anaphylaxis. Of these, ____ is also chemotactic for neutrophils.


C3a, C4a, C5a; C5a (a is for anaphylaxis)

18


• In the complement system, the membrane attack complex performs what function? What complement proteins combine to form the complex?


Cytolysis of target antigen; C5b, C6, C7, C8, C9

19

In the complement system, the cleavage of which plasma protein is the first shared step for both the alternative and classic pathways?


C5

20


• What are the two primary opsonins used to defend against bacteria?


C3b and immunoglobulin G

21

What two components prevent complement activation on self cells?


Decay-accelerating factor (DAF, also known as CD55) and C1 esterase inhibitor

22


• A new drug induces the classic pathway. It is analogous to which two antibody subtypes?


Immunoglobulins G and M (GM makes classic cars)

23

What are the three complement pathways, and how are they activated?


Classic, IgG/IgM antibody-antigen complex; alternative, spontaneous or microbe surface; & lectin, microbial surface molecules (mannose)

24


• What is mannose-binding lectin? Which complement pathway does it trigger?


Mannose-binding lectin recognizes mannose on bacterial surfaces and activates the lectin complement pathway (via MASP-1 or -2)

25

What are the alternative names for C3bBb, C3bBb3b, C4b2b, and C4b2b3b?


C3bBb ; C4b2b = C3 convertase, and C3bBb3b ; C42b3b = C5 convertase