T cell activation

Question 1

How are T cells activated?

Answer 1

1. Dendritic cells in the sites of infection take up pathogen derived antigens
2. When triggered by PAMPs and inflammation at the sites of infection, DC migrate to draining lymph nodes
3. They undergo maturation, enhancing their ability to present antigen and activate T cells
4. when they get to the lymph nodes, they interact with T cells in a dynamic process

Question 2

Naive T cells

Answer 2

Prior to recognition and antigen

Need several signals (MHC and costimulation) to become activated. Will die within weeks without antigen stimulation

Question 3

Effector T cell

Answer 3

Activated cell, antigen experienced, needs only 1 signal to respon to MHC-Peptide.

Short lived

Question 4

Memory T cell

Answer 4

Antigen experienced, remain in an easily activated state indefinitely, require only 1 signal to become re-activated

long lived

Question 5

Naive T cells require:

Answer 5

2 signals for activation.

1. specific MHC peptide complex
2. Costimulation through B7-1 or B7-2

Question 6

B7 interacts with

Answer 6

CD28

Question 7

B7-1 and B7-2

Answer 7

Costimulatory molecules that are uniquely expressde by DC, macrophages or B cells when they have been activated (or matured) by infection or inflammation.

Question 8

B7 other name

Answer 8

CD80 or CD86

Question 9

CD28 expressed by

Answer 9

T cells

Question 10

B7-1 and B7-2 are expressed by

Answer 10

antigen presenting cells

Question 11

Naive T cells reside in

Answer 11

secondary lymphoid organs

Question 12

Complex that stabilizes the interaction between T cell and antigen presenting cell

Answer 12

adhesion molecules

Question 13

Which of the following is considered signal 2 for T cell activation?

Answer 13

Costimulatory molecules

Question 14

What happens when T cells recognize their cognate antigen?

Answer 14

• TCR initiate signaling cascade through CD3 and CD4 or CD8
• Immune synapse forms at site of T cell-APC interaction
• T cell and APC remain in sustained interaction for many hours, up to and beyond 24hr.
• T cell disengages, divides and emigrates from lymph node to seek out infected cells in periphery

Question 15

ITAM

Answer 15

Immunoreceptor tyrosine based activation motifs

Question 16

In a resting T cell …

Answer 16

• ITAMs are not phosphorylated

Question 17

Binding of MHC ligand to T cell leads to

Answer 17

phosphorylation of the ITAMs by receptor associated kinases

Question 18

CD3

Answer 18

main signaling complex

Question 19

CD4

Answer 19

provides another important aspect of the singaling process

Question 20

Signaling at the cell membrane through signaling molecules ..

Answer 20

through calcium flux, leads to general activation of transcription factors.

Ultimately leads to cell division, proliferation, differentiation and different effector T cell functions

Question 21

synapse location

Answer 21

between T cell and APC
or

between T and B cell

Question 22

in peripheral SMAC

peripheral supra-molecular cluster (P-SMAC)

Answer 22

adhesion molecules

Question 23

central SMAC

Central supra molecular acticvation cluster(C-SMAC)

Answer 23

T cell receptor, signaling molecules

Question 24

most important cytokine for T cell proliferation

Answer 24

IL-2

binds to IL-2 receptor, expressed by activated T cell receptors with high affiity

Question 25

IL2 T cell Proliferation factor

Answer 25

**Positive feedback**

Question 26

Costimulatory signal and MCH signal leads to

Answer 26

activated T cell

Question 27

MHC (specific) signal alone on T cell leads to

Answer 27

anergic cell enter a period of nonresponsiveness, and then ultimately die

Question 28

Co-stimulatory signal alone leads to

Answer 28

no effect on T cell

Question 29

CD4 / T helper cell types

Answer 29

- TH1 cell - TH2 cell - TH17 cell - Tregs - Follicular helper T cell depends on the cytokines produced by the DC or APC during activation of T cell.

Question 30

Th1 cell

Answer 30

neutrophil, activated macrophage

Question 31

Th2 cell

Answer 31

mast cell, eosinophil, basophil, alternatively activated macrophage

Question 32

Th17 cell

Answer 32

neutrophil

Question 33

Follicular T helper cell associated with

Answer 33

Naive B cell

Question 34

CD8-T cell Type

Answer 34

Proliferation and Cytotoxic T cell (kills virus infected cells)

Question 35

if naive T cells is induced to undergo anergy, it must have recieved

Answer 35

Signal 1 without signal 2

Question 36

Cytotoxic T cells are activated by

Answer 36

Antigen presenting cells

Question 37

Cytotoxins (upregulated for killing) CD8

Answer 37

Perforin Granzymes Granulysin

Question 38

Cytokines (upregulated for killing) CD8

Answer 38

IFNy LT

Question 39

CTL (cytolytic T Cell) can use Fas ligand

Answer 39

to interact with Fas and send an apoptotic signal into the target cell Need **Signal 1 and 2**

Question 40

CTL are activated by one APC

Answer 40

but as they undergo proliferation and differentiation they are dependent on IL2

Question 41

When CD8-T cells move out into the periphery, they

Answer 41

recognize virally infetced target cells and can kill many different target cells without stopping. they are very efficienct. **SIGNAL 1** is sufficient to stop and kill the cell presenting an antigen

Question 42

granules of CD8 T cell

Answer 42

localizes to the area interacting with infected target cell and released the toxic granules onto the surface of the target cell