Type IV HSRs

Question 1

What are delayed type IV HSRs?

Answer 1

contact/skin permeable antigen activates TH1 cells leading to activation of macrophages

Question 2

Why are delayed type IV HSRs “delayed”?

Answer 2

requires the activation and recruitment of macrophages

Question 3

What happens in the sensitization phase of delayed type IV HSRs?

Answer 3

recognition, processing, presentation by MHC II
T cell activation and expansion
T memory cells made

Question 4

What are the 3 types of T memory cells?

Answer 4

central
effector
resident

Question 5

Where are central T memory cells located?

Answer 5

circulation/SLT

Question 6

Where are effector T memory cells located?

Answer 6

circulation/SLT and tissue

Question 7

Where are resident T memory cell located?

Answer 7

peripheral tissue

Question 8

CD45RA is expressed on what cells?

Answer 8

naive T cells

Question 9

CD45RO is expressed on what cells?

Answer 9

all T memory cells

Question 10

CCR7 is expressed on what cells?

Answer 10

naive T cells
central memory T cells

Question 11

CD103 is expressed on what cells?

Answer 11

resident memory cells

Question 12

Where are monocytes located?

Answer 12

blood

Question 13

Where are macrophages located?

Answer 13

tissue

Question 14

What happens in the effector phase of delayed type IV HSRs?

Answer 14

APC present and activate T memory cells = IFN-g and TNF production = macrophage/monocyte recruitment

Question 15

What does IL-12 do in the DT4HSR inflammatory loop?

Answer 15

induces more TH1 cells

Question 16

What does TNF do in the DT4HSR inflammatory loop?

Answer 16

macrophage activation and vascular permeability

Question 17

What does IL-8 do in the DT4HSR inflammatory loop?

Answer 17

recruits neutrophils

Question 18

What does CCL2 do in the DT4HSR inflammatory loop?

Answer 18

recruits monocytes

Question 19

Chronic macrophage activation due to the inability to clear antigen results in __________

Answer 19

granulomas

Question 20

What 2 things can induce granulomas formation?

Answer 20

silica
sutures

Question 21

What cytokines play a critical role in formation of granulomas and tissue damage?

Answer 21

IFN-g
TNF
(macrophage recruitment and release iNOS)

Question 22

TB skin test (mycobacterium) induce a pure _____ response

Answer 22

TH1

Question 23

Delayed type IV HSR are TH___ mediated

Answer 23

TH1

Question 24

Poison oak can be a TH___ mediated response but also a TH___

Answer 24

TH1
TH17

Question 25

What are 2 ways CD8 cells can be activate by DCs?

Answer 25

1. sequential activation 2. cross presentation

Question 26

What is sequential activation?

Answer 26

DC —CD4 T cell interaction increases B7 levels, then DC interacts/activates CD8 T cell

Question 27

What is cross presentation of CD8 T cells?

Answer 27

DC—CD4 T cell interactions, then changes their antigen processing to present on MHC I which can activate CD8 T cells (present extracellular antigen on MHC I)

Question 28

What is it called in cross presentation when DC switches thier antigen processing to present on MHC I?

Answer 28

cytosolic diversion

Question 29

TCR don't just recognize the peptide they also recognize _______

Answer 29

MHC

Question 30

What 2 things are special about NKT cells?

Answer 30

1. expresses invariant TCR (no memory) 2. senses glycolipids only

Question 31

NKT cells recognize ____ presented by ____ on APCs

Answer 31

glycolipids CD1d

Question 32

NKT cells DO NOT recognize…

Answer 32

MHC--peptide complex

Question 33

How does CD1a present lipids differently than how MHC presents peptides?

Answer 33

lipid is buried in CD1d and the A’ roof is what is recognized

Question 34

What expresses CD1a?

Answer 34

LC DCs

Question 35

What causes A’ roof to be blocked in CD1a?

Answer 35

healthy skin lipid head causes steric hinderance

Question 36

In the interference model of CD1a, binding of TCR is soley based on _____ not _____

Answer 36

CD1a not ligand

Question 37

What linkage in skin is abnormal in atopic dermatitis?

Answer 37

fillagrin

Question 38

What are corneocytes?

Answer 38

keratinocytes without nucleus

Question 39

Where are regular LC DCs located?

Answer 39

epidermis

Question 40

When LC DCs sample a foreign lipid with its CD1a what T cell subset is produced?

Answer 40

TH17

Question 41

How does the skin sense PPD from TB skin test?

Answer 41

injected directly into dermis by passing LC DCs and being sensed by dermal DCs and macrophages

Question 42

Only CD1___ has an A’ roof

Answer 42

CD1a

Question 43

What are 2 delayed type IV HSRs?

Answer 43

1. PPD (TB skin test) 2. urushiol (poison oak)