Innate Immunity

Question 1

What is the immune system?

Answer 1

Cells and organs that contribute to immunity defences against infection and non infectious conditions

Question 2

What is infectivity?

Answer 2

Ability of a pathogen to establish itself within a host

Question 3

What is virulence?

Answer 3

Capacity to cause tissue damage

Question 4

What is an infectious disease?

Answer 4

When a pathogen succeeds in evading and/or overwhelming the host’s immune defences

Question 5

What are the roles of the immune response?

Answer 5

Pathogen recognition
Containing + eliminating the infection
Regulating itself
Remembering pathogens

Question 6

What are features of innate immunity?

Answer 6

Fast
Lack of specificity
Lack of memory
No change in intensity

Question 7

What are features of adaptive immunity?

Answer 7

Slow
Specific
Immunologic memory
Change in intensity

Question 8

What are the first lines of defence?

Answer 8

Physical barriers
Physiological barriers
Chemical barriers
Biological barriers

Question 9

What are physical barriers?

Answer 9

Skin
Mucous membranes
Bronchial cilia

Question 10

What are physiological barriers?

Answer 10

Diarrhoea
Vomiting
Coughing
Sneezing

Question 11

What are chemical barriers?

Answer 11

Low pH

• skin
• stomach
• vagina

Antimicrobial molecules

• igA
• lysozyme
• mucus
• beta-defensins
• gastric acid

Question 12

What are biological barriers?

Answer 12

Normal flora - compete with pathogens

Question 13

What are the second line of defence?

Answer 13

Phagocytes
Chemicals
Inflammation

Question 14

What happens between phagocytes and microbes?

Answer 14

Recognition process

Killing process of infectious microbes

Question 15

What are the main types of phagocyte?

Answer 15

Macrophages
Monocytes
Neutrophils

Question 16

Where are macrophages found?

Answer 16

All organs

Question 17

What is the function of macrophages?

Answer 17

Ingest microbes
Present microbial antigens to T cells
Produce cytokines + chemokines

Question 18

Where are monocytes found?

Answer 18

Blood

Question 19

What is the function of monocytes?

Answer 19

Differentiate into macrophages

Question 20

Where are neutrophils found?

Answer 20

Blood

Question 21

What is the function of neutrophils?

Answer 21

Increase during infection
Recruited by chemokines
Ingest and destroy pyogenic bacteria

Question 22

What are other key cells in innate immunity?

Answer 22

Basophils
Eosinophils
Natural killer cells
Dendritic cells

Question 23

What is the function of basophils?

Answer 23

Early actors of inflammation

Important in allergic response

Question 24

What is the function of eosinophils?

Answer 24

Defence against multi-cellular parasites

Question 25

What is the function of natural killer cells?

Answer 25

Kill abnormal host cells

Question 26

What is the function of dendritic cells?

Answer 26

Present microbial antigens to T cells

Question 27

How do phagocytes recognise pathogens?

Answer 27

Pathogens have pathogen-associated molecular patterns (PAMPs) Phagocytes have pathogen recognition receptors (PRRs) Opsonisation

Question 28

What is opsonisation?

Answer 28

Enhanced attachment of phagocytes and clearance of microbes via opsonins

Question 29

What are some examples of opsonins?

Answer 29

``` C3b C4b IgG IgM CRP ```

Question 30

What are the phagocyte intracellular killing mechanisms?

Answer 30

Oxygen-dependent pathway | Oxygen-independent pathway

Question 31

What does the oxygen-dependent pathway use?

Answer 31

Toxic O2 products - hydrogen peroxide - hydroxyl radical - nitric oxygen

Question 32

What does the oxygen-independent pathway use?

Answer 32

``` Lysozyme Lactoferrin Cationic proteins Proteolytic enzymes Hydrolytic enzymes ```

Question 33

What chemicals make up the second line of defence?

Answer 33

Complement system | Cytokines

Question 34

What are the activating pathways for the complement system?

Answer 34

Alternative pathway | MBL pathway

Question 35

What is the alternative pathway?

Answer 35

Initiated by cell surface microbial constiuents

Question 36

What is the MBL pathway?

Answer 36

Initiated when MBL binds to mannose containing residues of proteins on microbes

Question 37

What is the role of C3a + C5a?

Answer 37

Recruitment of phagocytes

Question 38

What is the role of C3b + C4b?

Answer 38

Opsonisation of pathogens

Question 39

What is the role of C5-9?

Answer 39

Killing of pathogens - attack complex

Question 40

What is the role of cytokines/chemokines?

Answer 40

Chemoattraction Phagocyte activation Inflammation