Innate Immunity

Question 2

What are 2 examples of chemical defences?

Answer 2

1. antimicrobial defenses (eg. defensins)
2. enzymes (eg. lysozyme)

Question 3

What’s an example soluble factors?

Answer 3

complement proteins

Question 4

What are 4 examples of effector cells?

Answer 4

1. granulocytes
2. monocytes/macrophages
3. DCs
4. NK cells

Question 5

How do effector cells work?

Answer 5

recognise pamps and activate more effector cells

Question 6

How does lysozyme kill bacteria?

Answer 6

lysozyme catalyses hydrolysis linkages in peptidoglycan and digests cells wall, exposes cell membrane to outside

Question 7

How do defensins kill bacteria?

Answer 7

defensins disrupt and lyse bacterial cell wall - attracted by electrostatic attraction

Question 8

What is the key complement protein for marking a cell for destruction?

Answer 8

C3b

Question 9

What are 3 outcomes of the complement system?

Answer 9

1. migration of phagocytes to site of infection
2. opsonisation and phagocytosis of microorganisms
3. lysis of pathogens

Question 10

What are the 3 stages of complement action?

Answer 10

1. pattern recognition trigger
2. protease cascade amplification/c3 convertase
3. inflammation, phagocytosis, membrane attach

Question 11

What are the 3 main complement pathways?

Answer 11

1. alternative pathway
2. lectin pathway
3. classical pathway

Question 12

Briefly explain alternative pathway

Answer 12

pathogen surface creates local environment conducive to complement activation

Question 13

Briefly explain lectin pathway

Answer 13

mannose-binding lectin binds to pathogen surface

Question 14

Briefly explain classical pathway

Answer 14

c-reactive protein or antibody binds to specific antigen on pathogen surface

Question 15

What does C3b cause once bound to pathogen surface?

Answer 15

1. recruits inflam cells
2. opsonisation of pathogens (so, more uptake and killing by phagocytes)
3. perforation of pathogen cell membranes
4. eventually cell death

Question 16

Explain the ‘stranger/danger’ idea used by effector cells

Answer 16

stranger - common microbial structure which are not usually seen in the body
danger - changes in expression of self proteins

Question 17

How quickly do effector cells of innate system respond?

Answer 17

rapidly, minutes to hours
quick to act, quick to die

Question 18

What are granulocytes (provide 3 examples)

Answer 18

characterised by secretory granules in cytoplasm
polymorphonuclear cells
neutrophils, basophils, eosinophils

Question 19

What do neutrophils do?

Answer 19

phagocytosis and activation of bactericidal mechanisms

Question 20

What do eosinophils do?

Answer 20

essential for killing parasites; control infection by releasing cytotoxic granules

Question 21

What do basophils do?

Answer 21

drive innate immune response helping in anti-parasitic immunity

Question 22

How do eosinophils and basophils help in parasite resistance (refer to their size)

Answer 22

because they are small granulocytes, they recognise certain parts of a parasite and release granules to remove that aprt

Question 23

What are mast cells?

Answer 23

potent providers of histamine and cytokine release. associated with fighting parasites and inflam and allergen

Question 24

What does mast cell degranulation cause?

Answer 24

vasodilation, promotes inflammation, recruitment, more lymph flow to lymph node, cause muscular contraction for physical expulsion

Question 25

What are dendritic cells (DCs)

Answer 25

two types: migratory (mature), resident (resting)
sense pathogens, prevent antigen to T cells

Question 26

What are NK cells?

Answer 26

derived from same progenitor cells as lymphocytes
secrete anti-viral cytokines, lyse cells via release of cytolytic granules

Question 27

How does inflammatory response occur?

Answer 27

1. surface wound introduces bacteria, activating effector cells which release cytokines
2. vasodilation = more vascular permeability, so fluid, proteins, inflam cells leave blood and enter tissue
3. infected tissue is inflamed, causing redness, heat, swelling, pain

Question 28

What causes redness and heat in inflammation?

Answer 28

increase in vascular diameter and blood flow

Question 29

What causes swelling in inflammation?

Answer 29

increase in vascular permeability means more fluid leaks into tissue

Question 30

What causes pain in inflammation

Answer 30

inflammatory cells move into tissue, releasing mediators which stimulate nerve endings

Question 31

What produces complement proteins?

Answer 31

liver cells, macrophages, monocytes, epithelial cells