L7: T cell Effector Mechanisms

Question 1

Do activated CD4 T cells have L-selectin on their surface?

Answer 1

Yes. L-selectin lets T cells move into secondary lymphoid tissue. T helper cells are necessary for B cell activation in secondary lymphoid tissue

Question 2

Is VLA-4 present on CD8 activated cell surfaces?

Answer 2

Yes.

Question 3

What does the Fas ligand do?

Answer 3

It binds to infected cells and helps promote apoptotic death.

Question 4

What would the presence of many active CD8 T cells promote: TH1 or TH2 differentiation?

Answer 4

TH1. CD8 T cells secrete IFN-gamma, which is a strong promotor of TH1 differentiation. TH1 cells are also important in activation of new CD8 T cells.

Question 5

What is CD40 ligand?

Answer 5

helps activate macrophages and B cells by binding to CD40 on their cell surfaces

Question 6

What will IL-4 and IL-5 cause a TH0 to differentiate to?

Answer 6

TH2, which will generally activate B cells to make antibodies.

Question 7

What would IL-4 cause a TH0 to differentiate into?

Answer 7

TH2

Question 8

What would IL-12 cause a TH0 cell to differentiate into?

Answer 8

TH1

Question 9

What would IFN-gamma cause a TH0 to differentiate into?

Answer 9

TH1

Question 10

What produces IL-12?

Answer 10

APCs (antigen presenting cells)

Question 11

What do Treg cells do?

Answer 11

they down-regulate activation of naive T cells by producing large amounts of IL-10 and TGF-beta

Question 12

What is T-bet?

Answer 12

A transcription factor in TH1 cells that promotes production of IL-2 and IFN-gamma

Question 13

What is GATA-3?

Answer 13

A transcription factor in TH2 cells that promotes production of IL-4 and IL-5

Question 14

What is the transcription factor that promotes IL-2 production in TH!?

Answer 14

T-bet

Question 15

What is the transcription used by Treg cells to promote TGF-beta?

Answer 15

FoxP3 is the transcription factor

Question 16

What do granzymes do?

Answer 16

they re serine proteases which activate apoptosis once in cytoplasm of the target cell

Question 17

What is granulysin?

Answer 17

secretion of cytotoxic T cells that has antimicrobial actions and can induce apoptosis

Question 18

Do granzymes travel through perforin pores?

Answer 18

no, they are too big for the pores.
The pores damage the membrane and the host cell responds by endocytosing it. Granzymes bind to cation-independent mannose-6-P receptor (CI-MPR) and are taken into the cell during the endocytosis.
Reparative endocytosis.

Question 19

How does Fas ligand kill cells?

Answer 19

it activates the caspase cascade.

Question 20

How do CTLs focus their killing capability to only one cell and not the adjacent ones?

Answer 20

They polarize themselves so as to force the granule contents to dump in one specific site.

Question 21

Which type of T helper cell activates macrophages?

Answer 21

TH1 using CD40 and IFN-gamma.
B7 and MHC class I and II are upregulated after that.

Question 22

What is the only way a TH1 cell can kill another cell?

Answer 22

Using Fas ligand, they can kill infected, worn out macrophages.

Question 23

What will IL-3 and GM-CSF released from a TH1 molecule do?

Answer 23

promote differentiation of macrophages in the bone marrow.

Question 24

What does CKCL2 do? Where does it come from?

Answer 24

It is released by TH1 cells and causes macrophages to accumulate at site of infection

Question 25

What do TNF-alpha and LT when released from TH1 cells?

Answer 25

they induce macrophage adhesion and exit from blood vessels at sites of infection

Question 26

What does TNF-alpha do to macrophages?

Answer 26

Activates macrophages.

Induces NO production

Question 27

What does GM-CSP do to hematopoietic cells?

Answer 27

increases production of granulocytes, macrophages and dendritic cells

Question 28

What are JAKs? STATS?

Answer 28

Janus Kinases.
When cytokine receptors on cells are activated, JAKs become activated and phospharylate themselves. This attracts a STAT, which binds to the JAK and gets phosphorylated. The phosphoyrlated STAT then binds to another phosphorylated STAT and forms a dimer. This dimer then moves into nucleus and binds to DNA to initiate gene transcription

Question 29

How do granulomas form?

Answer 29

occurs when microbes resist destruction by macrophages. The function is to prevent dissemination of microbe.
IFN from TH1 cells induces granuloma formation.
A defect in CD40 will prevent granuloma formation.

Question 30

How does CD40 deficiency prevent granuloma formation?

Answer 30

without CD40, T helper cells can not activate macrophages.