Inate Immunity

Question 1

Innate immunity definition:

Answer 1

Natural immunity that is present from birth.
Non-specific.

Question 2

Innate immunity examples (5):

Answer 2

Physical barriers
Inflammatory mediators
Complement proteins
Acute phase proteins
Immune cells

Question 3

Skin structure:

Answer 3

Tightly packed, highly keratinised cells.
Contains sebaceous glands which secrete hydrophobic oils, lysosomes and ammonia

Question 4

Physiological factors of skin:

Answer 4

Low pH (5.5)
Low oxygen tension

Question 5

Where do you find mucous membranes?

Answer 5

Line all body cavities that are in contact with the external environment

Question 6

How does mucus kill pathogens?

Answer 6

Traps bacteria
Contains lysosomes and defensins that kill pathogens

Question 7

What does commensalism bacteria do?

Answer 7

Competes with pathogens for resources and produce fatty acids and bactericidins that stops pathogens growing

Question 8

What do interferons do?

Answer 8

Signal to uninflected cells to:
- Destroy RNA and reduce protein synthesis
- Undergo apoptosis

Question 9

How are immune cells activated?

Answer 9

By interferons

Question 10

What are cytokines?

Answer 10

Interferons released by virally infected cells

Question 11

What do macrophages do?

Answer 11

Phagocytose bacteria

Question 12

Phagocytosis process (7):

Answer 12

1. PRRs binds to PAMPs on pathogen signalling formation of the phagocytic cup
2. Cup extends around the pathogen and pinches off forming a phagosome
3. Phagosome fuses with lysosome forming a phagolysosome
4. Pathogen killed and contents degraded
5. Debris released into extracellular fluid
6. Pathogen-derived peptides are expressed on special cell surface receptors (MHC-II)
7. Pro-inflammatory mediators released (TNF⍺) causing acute inflammation

Question 13

How do innate immune cells recognise pathogens?

Answer 13

Pathogens express signature molecules not found on/in human cells called PAMPS

Question 14

What does PAMPS stand for?

Answer 14

Pathogens associated molecular patterns

Question 15

What does PAMPS stand for?

Answer 15

Pathogens associated molecular patterns

Question 16

What are PRRs?

Answer 16

Pattern-recognition receptors on innate immune cells

Question 17

What are MHC-II?

Answer 17

Special cell surface receptors

Question 18

What is TNF⍺?

Answer 18

Pro-inflammatory mediator

Question 19

Role of mast cells:

Answer 19

Deal with pathogens too large for phagocytosis

Question 20

How do mast cells kill pathogens?

Answer 20

1. PRRs on mast cell bind to PAMPs on pathogen
2. Mast cell is stimulated to release pre-formed pro-inflammatory substances causing degranulation

(As this happens mast cell begins to produce new pro-inflammatory substances)

Question 21

Examples of pro-inflammatory substances:

Answer 21

Histamine
Tryptase

Question 22

What is transendothelial migration?

Answer 22

The recruitment of neutrophils to the site of infection/damage during acute inflammation

Question 23

Transednothelial migration steps:

Answer 23

1. Loss of intravascular fluid during inflammation causes slower blood flow, allowing neutrophils to migrate
2. Neutrophils bind to adhesion molecules on the endothelial cells
3. Neutrophils migrate across the endothelium via diapedesis
4. Once in the tissues, the neutrophils travel to site of injury via chemotaxis
5. Neutrophils are activated by PAMPs and pro-inflammatory mediators

Question 24

Where do neutrophils travel in a vessel?

Answer 24

Close to endothelial cells of vessel

Question 25

Killing mechanisms of neutrophils (3):

Answer 25

Phagocytosis Degranulation NETs

Question 26

Phagocytosis in neutrophils:

Answer 26

Phagolysosomal killing via production of reaction oxygen species (ROS)

Question 27

Degranulation in Neutrophils

Answer 27

Release of anti-bacterial granules

Question 28

NETs in neutrophils:

Answer 28

Release of a net-like structure that traps pathogens, leading to phagocytosis

Question 29

Modes of ingestion in neutrophils:

Answer 29

Endocytosis Pinocytosis Phagocytosis

Question 30

Features of endocytosis in neutrophils:

Answer 30

Receptor mediated Molecules that bind to membrane receptors are internalised Important in adaptive immunity

Question 31

Pinocytosis in neutrophils:

Answer 31

Ingestion of fluid of surrounding cells

Question 32

What are Natural Killer (NK) cells?

Answer 32

Lymphocytes involved the rejection of tumors and virally infected cells

Question 33

What do NK cells respond to?

Answer 33

Reduced levels of MHC class 1 in virally infected and cancerous cells

Question 34

How to NK cells kill pathogens?

Answer 34

By degranulation