4 Cell Mediated Immunity (1 Hour)

Question 1

Where do T cells leave the lymph nodes through?

Answer 1

HEVs

Question 2

What cell alone is capable of activating naive T cells?

Answer 2

Dendritic cells

Question 3

What can activate memory T cells?

Answer 3

B cells and macrophages

Question 4

What activates B cells and macrophages?

Answer 4

CD4+ T cells

Question 5

What is CD25 also known as? What does it function in?

Answer 5

IL2r, autocrine growth signal

Question 6

How are T cells trapped? Why are they?

Answer 6

Down regulation of chemokines that would cause the T cell to leave the node; they need to stay to activate B cells

Question 7

In the T cell immune synapse, what is the function of the CD4/8 interaction with HLA?

Answer 7

Signal transduction

Question 8

What is the function of the CD28 on T cells interacting with the CD80/B7 on APCs?

Answer 8

Costimulation

Question 9

What two interactions hold T cells and APCs together?

Answer 9

LFA (T) -> ICAM1 (APC)

CD2 (T) -> LFA3 (APC)

Question 10

What is often needed for CD8 T cell activation? Explain

Answer 10

Cross presentation

This is when you have Th cells costimulating DC with cytokines to get CD8 and you also get DC presenting antigen directly from APC to CD8

Question 11

What differentiates a Th1? What TF is required?

Answer 11

IFNg and IL12, T-bet

Question 12

What differentiates Th2? What TF is involved?

Answer 12

IL4, GATA-3

Question 13

What differentiates Th17? What TF is involved?

Answer 13

TGFb, IL6, IL23; RORgT

Question 14

What does Th1 produce?

Answer 14

IFNg and TNFa

Question 15

What do Th1 activate?

Answer 15

Macrophages

Question 16

What do Th2 activate?

Answer 16

Eosinophils and alternative macro

Question 17

What do Th17 produce? What does this do?

Answer 17

IL17, 22

Activates neutro through IL17
Increased barrier function through IL22
Role in IBD, RA, MS

Question 18

What do bacterial super antigens do? What do they bind to?

Answer 18

They activate T cells without co-stim

They act on the b portion of the TCR

Question 19

An effector T cell is able to respond to antigen in the absence of

Answer 19

CD28(T)/CD80(DC) interaction

Question 20

What 2 things do activated T cells start making?

Answer 20

Co stimulatory molecules (CD28)
Also inhib (CTLA4) (binds to CD80 instead)

Question 21

What happens during activation that allows T cells to respond to the site?

Answer 21

Integrins become high affinity

Question 22

What increases HLA expression on CTL?

Answer 22

Type 1 IFNs

Question 23

What does the Th1 make to stimulate CTL?

Answer 23

IL2

Question 24

What is Fas also known as?

Answer 24

CD95

Question 25

How does CTL kill a cell?

Answer 25

Perforin and granzymes | Or FasL binding to Fas on target

Question 26

Why does CTL kill in clusters? What do they produce?

Answer 26

IFNa/b to slow viral replication and also increases MHC 1 on other cells To ensure that the virus is cleared around the initial infected cell

Question 27

How does NK kill?

Answer 27

Same way as CTL

Question 28

What enhances NK killing

Answer 28

IFNa, IFNb, IL12

Question 29

What cells act in Ab dependent cell-mediated cytotoxicity?

Answer 29

NK, macro, neutrophil, eosinophil

Question 30

What causes CTL exhaustion

Answer 30

CTLA4 on T cell interacting with APC

Question 31

What do memory T cells require for survival?

Answer 31

IL7 (BM and thymic stromal cells) and IL15 (Th2)

Question 32

Why are memory responses faster?

Answer 32

Mem T cells can be activated w/o co-stim

Question 33

What do Treg express? What TF is of interest?

Answer 33

CTLA4 and CD25 (IL2r) FOXp3

Question 34

How does EBV evade the immune system?

Answer 34

Shuts down proteosome Produces IL10 to calm down macrophage

Question 35

What does IFNg stimulate?

Answer 35

``` Activates macrophages (classical) Activates B cell to stim. complement binding Stim. class 2 HLA and CD80 ```