Innate Immunity 6

Question 1

what type of cells are NK cells?

Answer 1

innate lymphoid cells (ILCs)

Question 2

what cells do NK cells share a progenitor with? what is the progenitor called?

Answer 2

share a progenitor with B and T cells

progenitor = common lymphoid progenitor

Question 3

are NK cells innate or adaptive?

Answer 3

innate

Question 4

how many types of ILCs are there? and their names?

Answer 4

3

ILC1, ILC2, ILC3

Question 5

what are 2 differences btwn NK/ILCs compared to other cells from the common lymphoid progenitor (B and T cells)

Answer 5

1. part of innate response
2. they are not antigen specific

Question 6

where are ILCs located?

Answer 6

in tissues, adjacent to mucosal layer

Question 7

ILCs play an important role in ______ immunity

Answer 7

ILCs play an important role in mucosal immunity

Question 8

describe the specificity of ILCs

Answer 8

specific for TYPE of pathogen, but not for epitope/antigen

Question 9

where are NK cells located?

Answer 9

in tissues or circulation

Question 10

what is the role of ILCs?

Answer 10

contribute to defense against specific pathogen

Question 11

what is the role of NK cells?

Answer 11

directly kill stressed cells

Question 12

why is it important that NK cells are in circulation?

Answer 12

this allows them to travel to site of infection

Question 13

do ILCs and NK cells have PRRs?

Answer 13

ILCs don’t have PRRs but a subset of NK cells have PRRs

Question 14

how are ILCs/NK cells activated if they don’t have PRRs?

Answer 14

activated by cytokines from DCs or other cells

Question 15

what is the general role of ILCs and NK cells?

Answer 15

once they are activated, there is intracellular signaling which allows for the release of more cytokines to contribute to pathogen killing

Question 16

what type of pathogen do NK cells and ILC1 target?

Answer 16

intracellular pathogens

Question 17

what type of pathogen do ILC2 and ILC3 target?

Answer 17

extracellular pathogens

Question 18

describe the role of ILC1

Answer 18

allows for killing of intracellular pathogens

Question 19

describe a role of ILC2

Answer 19

increases mucous production to wash away parasite in intestinal lumen for ex.

Question 20

describe a role of ILC3

Answer 20

recruits neutrophils to release antimicrobial peptides to kill extracellular bacteria and fungi

Question 21

can ILC2 be found in circulation? what is the evidence for this (experiment)

Answer 21

experiment shows ILC2 can be found in lymphatic circulation

in experiment where cytokine (IL-25) was added to ilea of gut, can see ILC2 in lymphatic vessel, while no ILC2 was found in non-IL-25 treated ilea

Question 22

are ILCs solely tissue residents?

Answer 22

NO, in some cases they can travel

Question 23

how do NK cells work?

Answer 23

when host cells become stressed, they express stress proteins

NK cells have receptors for these stress proteins and can kill the host cell

Question 24

what are 3 stressors that could cause expression of stress proteins on host cells?

Answer 24

1. infection (main)
2. cancer/tumour (malignant transformations)
3. damage, other stressors

Question 25

how do NK cells kill the host cell? (not receptors)

Answer 25

by producing cytokines that induce adaptive responses against the host cell

Question 26

how do NK cell receptors change?

Answer 26

they don’t –> receptors are encoded in the germline

Question 27

what are the 2 types of NK cell receptors?

Answer 27

1. activating receptors
2. inhibitory receptors

Question 28

what do NK cell receptors recognize?

Answer 28

1. MHC class I molecules
2. MHC class I-like molecules

Question 29

what does the NK cell do in a normal context?

Answer 29

receives activating and inhibitory signals but there are more inhibitory signals which override the activating signals and PREVENT ACTIVATION OF NK CELL –> host cell survives

Question 30

what does the NK cell do in a disease context? (MOST COMMON)

Answer 30

lack of MHC-1 so there is no inhibitory signals –> only activating signal is received so NK cells release granules to poke holes in the cell to trigger apoptosis

lack MHC-1 bc pathogen prevents antigen presentation, so cell very damaged!

Question 31

what does the NK cell do in a disease context (LESS COMMON)

Answer 31

host cell can express Death Receptor which is targeted by TRAIL ligand on NK cells –> cleaves pro-caspase 8 into caspase 8 and causes self-induced apoptosis

Question 32

what is different about the TRAIL/DR mechanism of NK killing vs the more common mechanism?

Answer 32

there are no activating or inhibitory signals –> just the binding of TRAIL to DR causes apoptosis