Intracellular immunity (year 2)

Question 1

intracellular invasion will lead to what type of antigen presentation?

Answer 1

MHC 1

Question 2

what type of cells recognise antigen on MHC 1?

Answer 2

CD8 T cells

Question 3

how quickly are interferons secreted?

Answer 3

quickly - within hours of infection

Question 4

interferons have antiviral activity, what does this mean?

Answer 4

protect neighbouring cells from infection by binding/blocking viral receptors

Question 5

what are the two types of interferons?

Answer 5

I and II

Question 6

give examples of type I interferons

Answer 6

IFNalpha and IFNbeta

Question 7

give examples of a type II interferon

Answer 7

IFNgamma

Question 8

where ate type I interferons released from?

Answer 8

tissue cells such as fibroblasts

Question 9

what do type I interferons do?

Answer 9

stimulate NK cell activity and secretion of IFNgamma

Question 10

where are type II interferons secreted from?

Answer 10

secreted from activated T and NK cells

Question 11

what is the function of type II interferons?

Answer 11

prevent viral growth by the induction of nitric oxide secretion
they also activate macrophages

Question 12

what T helper cell response is crucial for removal of intracellular pathogens?

Answer 12

1

Question 13

how do cytotoxic CD8 T cells kill cells with intracellular pathogens?

Answer 13

release cytotoxic granules containing granzymes and perforin which lead to a loss of membrane integrity, this process is non-specific
they are also able to cause apoptosis by using Fas ligand

Question 14

how do the macrophages activated by Th1 cells cause cell death?

Answer 14

express nitric oxide and the oxygen radicals that cause host cell death
this is not MHC restricted or specific

Question 15

what are NK cells recruited by that they also secrete?

Answer 15

IFNgamma

Question 16

what do NK cells recognise on cells that determine if the host cell is destroyed?

Answer 16

recognise the base of MHC not the antigen

if MHC isn’t present then the cell is targeted for destruction

Question 17

why do NK cells target host cells that don’t express MHC complexes?

Answer 17

it is common for viral infections to down regulate MHC expression on the surface

Question 18

what are common ways viruses try to evade immune detection?

Answer 18

downregulating MHC expression
mutation
changing antigen shape

Question 19

what are the four types of pathogenesis shown by viruses?

Answer 19

lytic - destruction of host cells
persistent - slow release of viral particles damaging cells
latent - delay between infection and symptoms appearing
transformation - form tumours

Question 20

what are some adverse consequences to viral immunity?

Answer 20

excessive immune response leading to damage of infected/neighbouring cells

Question 21

why do protozoal infections require both humeral and cell mediated immune responses?

Answer 21

they have two stages of their lifecycle including an extracellular and intracellular stage

Question 22

what drives the humeral immune response and what does it aim to do?

Answer 22

Th2 and aims to control parasite numbers in blood/tissue

Question 23

how do protozoa invade immunity?

Answer 23

resistant to complement
survive inside phagocytes
manipulate dendritic cells
inhibit motility
inhibit cytokine production

Question 24

name the factors of bacterial pathogenesis

Answer 24

exotoxin, endotoxin, superantigen

Question 25

describe exotoxins of bacteria

Answer 25

these are secreted by the bacteria and are extracellular, they are usually targeted by neutralising antibodies

Question 26

name the two main endotoxins

Answer 26

LPS and lipid A

Question 27

what are endotoxins?

Answer 27

these are toxins that are attached to bacteria

Question 28

where is LPS found and how does it work?

Answer 28

gram negative bacteria

activates macrophages to release inflammatory cytokines leading to tissue degredation

Question 29

how do lipid A work?

Answer 29

only toxic if it enters the bloodstream where it activated coagulation and causes sepsis

Question 30

what are superantigens?

Answer 30

polyclonal T cell activators

Question 31

how do superantigens work?

Answer 31

hyper stimulate the immune system causing fever and vomiting

they also lead to shock causing organ failure and circulatory collapse

Question 32

what is immunopathy?

Answer 32

damage to infected and bystander tissue due to over stimulation of cytokine production and complement activation by endotoxins