Lecture 20

Question 1

What is signal 1 for T cell activation?

Answer 1

When the t cell receptor binds to MHC presenting antigen.

Question 2

What is signal 2 for T cell activation?

Answer 2

When CD28 on the T cell binds to CD80 on the antigen presenting cell.

Question 3

What are the 5 steps for T cell activation?

Answer 3

Antigen specific binding of TCR and MHC (signal 1)

Co-receptor binding of CD4/8 to MHC

Adhesion between LFA-1 and ICAM

Co-stimulation with the binding of CD28 and CD80

Inflammatory signals- APC and IL-12

Question 4

What is the purpose of CD4/CD8 binding to MHC?

Answer 4

Stabilises the low-affinity binding of the TCR to MHC

Question 5

True or false: CD4 binds to MHCI

Answer 5

False: CD4 binds to MHCII

Question 6

True or false: CD8 on the antigen presenting cell binds to MHCI on the T cell

Answer 6

False: CD8 on the T cell binds to the MHCI on the antigen presenting cell

Question 7

True or false: LFA-1 on the T cell binds to MHCII on the antigen presenting cell

Answer 7

False: LFA-1 on the T cell binds to ICAM-1 on the antigen presenting cell

Question 8

What is the purpose of LFA-1 and ICAM-1 binding?

Answer 8

Further stabilises the interaction between the T cell and the APC. This allows for binding for long enouh to establish a good signal to the T cell.

Question 9

True or false: The binding of LFA-1 and ICAM-1 is signal 2 for the T cell

Answer 9

False: The binding of CD28 and CD80 is signal 2 to the T cell

Question 10

True or false: Signal 1 (binding of the TCR and MHC) is enough of a signal to get the T cell going but signal 2 makes the response much greater and more efficient.

Answer 10

False: Without signal 1 and 2 the T cell does nothing

Question 11

What cytokine promotes the T cell response?

Answer 11

IL-12

Question 12

True or false: The production of interleukin 12 (IL-12) by the antigen presenting cell promotes the T cell response.

Answer 12

True :)

Question 13

What is the immunological synapse? What is its function?

Answer 13

It is the connection between the T cell and the APC. It requires reorganisation of T cell membrane proteins. It regulates signalling.

Question 14

What are 4 things that are released by the T cell after its activation? What is the function?

Answer 14

IL-2: T cell proliferation and survival

Perforin/Granzyme: T cell cytotoxic function

Cytokines: Antibody production

IFN-gamma: activates macrophages

Question 15

What is the signalling unit of the TCR?

Answer 15

CD3

Question 16

Two protein kinases, LCK and Fyn, are able to phosphorylate what when antigen binds to TCR? What changes occured to this protein when antigen bound?

Answer 16

Are able to phosphorylate ITAMs which is a subunit of CD3, a unit of the TCR. When antigen binds, the TCR undergoes a conformational change which also changes CD3, exposing regions of ITAMs that were not exposed previously.

Question 17

LCK is constitutively associated with what?

Answer 17

LCK is constitutively associated with cytoplasmic domains of CD4 and CD8.

Question 18

Fyn associates weakly with what?

Answer 18

Zeta chains of CD3.

Question 19

Once ITAMs have been phosphorylated, what can bind?

Answer 19

Zap70

Question 20

Once ZAP70 has been phosphorylated by LCK, what does it go onto phosphorylate?

Answer 20

Scaffold proteins LAP and SLP76

Question 21

Once the scaffold proteins LAP and SLP76 have been phosphorylated, what does it recruit?

Answer 21

PLC gamma

Question 22

When PLC gamma has been recruited and phosphorylated by LCK, what does it activate?

Answer 22

NFKB