Innate Immunity

Question 1

Where are complement proteins made? How many are there?

Answer 1

Liver - 20

Question 2

What molecule binds to the surface of bacteria in all pathways of complement system? What can this molecule be cleaved to in order to opsonize invaders and tag them for phagocytosis by macrophages?

Answer 2

C3b

iC3b - opsonization/phagocytosis

Question 3

What attack complex forms and lyses microbes in the complement system?

Answer 3

MAC

Question 4

Why aren’t human cells attacked by MAC complexes? (2 reasons)

Answer 4

1. MCP on surface of human cells clips C3b to inactive form

2. DAF - decay accelerating factor accelerates destruction of C3 convertase (C3bBb)

Question 5

What protein cleaves C3 to make C3b?

Answer 5

C3bBb aka C3 convertase

Question 6

What protein forms from the binding of C3b and C3 convertase?

Answer 6

C3bBb3b (C5 convertase)

Question 7

What does C5 convertase do?

Answer 7

Cleaves C5 to make C5b

Question 8

What complement proteins combine to form the MAC (membrane attack complex)?

Answer 8

C5b, C6, C7, C8, C9

Question 9

What is the name of the pathway that acts spontaneously and on microbial surfaces to form the MAC complex?

Answer 9

Alternative pathway

Question 10

What is the name of the pathway that makes C3b non-spontaneously to form the MAC complex?

Answer 10

Lectin pathway

Question 11

Besides C3bBb, what is another C3 convertase (used in lectin and classical pathways)?

Answer 11

C4b2a

Question 12

What molecule does the lectin pathway use to bind to MASP and make C4b?

Answer 12

MBL (mannose-binding lectin)

Question 13

What is the name of the pathway that is antibody dependent to form MAC?

Answer 13

Classical pathway

Question 14

What are the three stages of readiness for macrophages?

Answer 14

1. Resting state - scavengers
2. Primed state - barriers have been penetrated
3. Hyperactivated/killing state - attain direct signals from invader

Question 15

What cytokine do neutrophils produce to draw other immune cells?

Answer 15

TNF

Question 16

What molecules are present on endothelial cells that allow neutrophils to bind? What molecules are present on the neutrophils to allow them to bind?

Answer 16

Endothelial cells - ICAMs and selectins (SEL)

Neutrophils - integrins, selectin ligand (SLIG)

Question 17

What bacterial protein and complement protein trigger neutrophil expression of integrins?

Answer 17

C5a and LPS

Question 18

How do natural killer cells destroy cells? What types of receptors do NK cells recognize and thus allow to survive?

Answer 18

Inject granzyme B into target cell, which stimulates caspases and interact with Fas on surface of target cell–> induce apoptosis

NK cells recognize MHC-I

Question 19

What molecule and cytokines activates NK cells for killing?

Answer 19

LPS (on bacterial cell walls)

IFN-a, IFN-b (given off by cells when attacked by viruses)

Question 20

What cytokine do NK cells release when activated? What does this stimulate?

Answer 20

IFN-gamma

Stimulates macrophages to make TNF and IL-12

Question 21

What cytokine, made by NK cells themselves, as well as by macrophages, tells the NK cells to proliferate?

Answer 21

IL-2