Immunology: Late Innate Immune Responses

Question 1

what are PAMPS

Answer 1

• pathogen-associated molecular patterns

- found on antigens

Question 2

what are PRRs

Answer 2

• pattern recognition receptors

- found on innate immune cells cell membrane and detect IC/EC pathogens

Question 3

when the complement system is activated what does it promote

Answer 3

• acute inflammation
• pathogen killing
• pathogen opsonisation
• leukocyte recruitment

Question 4

draw the diagram of complement system activation

Answer 4

**

Question 5

how is MAC formed and what does it do

Answer 5

• C5b associates with another protein to form pore channels

- this allows salt and water into the pathogen causing it to swell and burst

Question 6

what complement protein is a good opsonin

Answer 6

C3b

Question 7

what complement proteins are anaphylatoxins

Answer 7

C3a and C5a

Question 8

what do anaphylatoxins do

Answer 8

• promote local inflammation and leukocyte recruitment by activating mast cell
• act directly on local bv to produce vascular changes

Question 9

what vascular changes does acute inflammation promote

Answer 9

• loss of endothelial tight junctions
• post-capillary vasocilation
• increased permeability
• endothelial expression of adhesion molecules

Question 10

what cellular changes occur during acute inflammation

Answer 10

• neutrophils are recruited and activated, adhesion molecules expressed, transendothelial migration
• monocytes recruited

Question 11

describe transendothelial migration

Answer 11

• neutrophil margination and inflammatory sites
• neutrophils bind to adhesion molecules
• migration across endothelium by diapedesis
• chemotaxis transport neutrophils in tissues
• PAMPs and TNF-alpha activate neutrophils

Question 12

how do neutrophils pahgocytose pathogens

Answer 12

• phagolysosomal killing

- ROS, respiratory burst, ROS produced and release into phagosome (H202)

Question 13

how do neutrophils kill pathogens (3)

Answer 13

• phagocytosis
• degranulation
• NETs

Question 14

describe neutrophil degranulation

Answer 14

anti-bacterial proteins release into ECF killing pathogens

Question 15

what is the downfall to neutrophillic degranulation

Answer 15

can cause tissue damage and potentially systemic inflammation

Question 16

when does neutrophillic degranulation occur

Answer 16

after phagocytosis to kill all nearby EC pathogens

Question 17

describe pathogen killing via NETs

Answer 17

• NETs composed of DNA, proteins and enzymes are release from the cell
• this immobilised the pathogen to prevent spreading but also aids phagocytosis
• minimum host damage but kills cell

Question 18

what drives and mediates the acute phase response

Answer 18

• pro-inflammatory mediatoirs drive

- mediated by liver hepatocytes producing acute phase proteins

Question 19

acute phase proteins

Answer 19

• C3 and MBL - complement

- CRP - opsonin

Question 20

what do virally infected cells release

Answer 20

interferons

Question 21

what do interferons do

Answer 21

• interfere with viruses ability to replicate within host cells and therefore prevent viral replication
• signal to cells to produce anti-viral factors that interfere with viral replication and protect the cell
• signals to other cells that a virus is present

Question 22

when neraby cells recieve signal of a viral presence what happens

Answer 22

they produce MHC 1 and surveying T cells identify and eliminate the virus

Question 23

what os the role of NK cells

Answer 23

recognise and destroy virally-infected and cancer cells

Question 24

what happens to NK cells during acute inflammation

Answer 24

recruited to site of inflammation and are longer lived than neutrophils

Question 25

what do NK cells respond to

Answer 25

decreased levels of MHC 1 which occurs in virally-infected and cancer cells

Question 26

how do NK cells kill their targets

Answer 26

release cytotoxic molecules making the abnormal cell undergo apoptosis