Lecture 20 Flashcards
What is signal 1 for T cell activation?
When the t cell receptor binds to MHC presenting antigen.
What is signal 2 for T cell activation?
When CD28 on the T cell binds to CD80 on the antigen presenting cell.
What are the 5 steps for T cell activation?
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
What is the purpose of CD4/CD8 binding to MHC?
Stabilises the low-affinity binding of the TCR to MHC
True or false: CD4 binds to MHCI
False: CD4 binds to MHCII
True or false: CD8 on the antigen presenting cell binds to MHCI on the T cell
False: CD8 on the T cell binds to the MHCI on the antigen presenting cell
True or false: LFA-1 on the T cell binds to MHCII on the antigen presenting cell
False: LFA-1 on the T cell binds to ICAM-1 on the antigen presenting cell
What is the purpose of LFA-1 and ICAM-1 binding?
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.
True or false: The binding of LFA-1 and ICAM-1 is signal 2 for the T cell
False: The binding of CD28 and CD80 is signal 2 to the T cell
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.
False: Without signal 1 and 2 the T cell does nothing
What cytokine promotes the T cell response?
IL-12
True or false: The production of interleukin 12 (IL-12) by the antigen presenting cell promotes the T cell response.
True :)
What is the immunological synapse? What is its function?
It is the connection between the T cell and the APC. It requires reorganisation of T cell membrane proteins. It regulates signalling.
What are 4 things that are released by the T cell after its activation? What is the function?
IL-2: T cell proliferation and survival
Perforin/Granzyme: T cell cytotoxic function
Cytokines: Antibody production
IFN-gamma: activates macrophages
What is the signalling unit of the TCR?
CD3
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?
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.
LCK is constitutively associated with what?
LCK is constitutively associated with cytoplasmic domains of CD4 and CD8.
Fyn associates weakly with what?
Zeta chains of CD3.
Once ITAMs have been phosphorylated, what can bind?
Zap70
Once ZAP70 has been phosphorylated by LCK, what does it go onto phosphorylate?
Scaffold proteins LAP and SLP76
Once the scaffold proteins LAP and SLP76 have been phosphorylated, what does it recruit?
PLC gamma
When PLC gamma has been recruited and phosphorylated by LCK, what does it activate?
NFKB
