Week 4 Flashcards
What are the main roles of T cells ?
Find and kill infected cells
Activate other immune cells
Cytokine production
Co-ordinate and regulate the immune response
What are the 4 stages of T cell response?
1) Detect the presence of an infected cell.
2) Pass the external signal across the cell membrane.
3) Activate the relevant biochemical pathway.
4) Produce the cellular response.
What type of antigens are used in the MHC class I antigen presentation pathway?
Endogenous
What type of antigens are used in the MHC class II antigen presentation pathway?
Exogenous
What type of T cells and MHC are used against endogenous antigens.
MHC class I with CD8+ T cells
What type of T cells and MHC are used against exogenous antigens.
MHC class II with CD4+ T cells
What type of T cells are CD8+ T cells?
Cytotoxic
What type of T cells are CD4+ T cells?
Helper T cells
How many subunits does the T-cell proper structure have?
4
How does the differential structure on alpha and beta chains alter antigen binding?
It does not significantly change antigen binding.
When and how does the ITAM receptor on a T cell receptor change?
The structure has a conformational change when an antigen becomes bound to the T cell.
What happens when the ITAM receptor on a T cell receptor is activated?
The ITAM will start phosphorylating other proteins.
What type of receptors do all T cells have?
CD3
How are T cell receptors degenerative?
Many T cell variants recognise the same antigen.
What process allows signals to be transduced cross the T cell membrane from the T cell receptor?
Dimerisation
What do T cells initially use to bind to APC cells?
Low affinity LFA-1 and CAM-1 interactions.
How do T cells begin to have stronger binding with antigen presenting cells?
Binding of T cell receptors signals LFA-1. Conformational changes in LFA-1 increase the affinity and prolong cell-cell contact.
What is ICAM-1 recognised by?
LFA-1 protein on T cells.
Why do T cells use 2 different receptor types to bind to antigen presenting cells?
This allows binding for a longer amount of time and gives T cells longer to do their jobs and transduce the signal.
What are the purpose of CD28 T cell receptors?
Expressed to recognise if the antigen derives from the innate immune response.
What are the purpose of CD80 T cell receptors?
They bind to CD28and further strengthen the response and stabilise the cellular interactions.
What are the purpose of Ox40L T cell receptors?
They connect to ligands and stabilise the connection and also increase the length of cellular interactions.
In resting T cells, are ITAMS phosphorylated or not?
No
What causes ITAMS on T cells to become phosphorylated?
Binding of ligands
What happens to ITAMS on T cells once a ligand binds?
Binding of the ligands causes phosphorylation of ITAMS when the co-receptor binds to the MHC ligand.
How does phosphorylation of a molecule cause activation?
Causes the molecule to become more negatively charged. This may change the shape of the protein and may lead to its activation or inactivation.
What atoms carry the largest quantity of negative free energy?
Phosphorus
Why are phosphorus atoms used so frequently in cell signalling and activation?
They carry a high amount of negative free energy.
What is ‘different’ about ZAAP protein?
It is not static and can move across the cytoplasm and interact with LAT complexes.
What is the benefit of ZAAP in terms of T cells and how does it cause this?
ZAAP can phosphorylate ADAP which then activates a series of proteins and results in intern interactions. This aids cell adhesion.
What changes in T cells can be caused by NAFT phosphorylation?
Activation of transcription mechanisms and alteration of gene expression.
Why are drugs used to inhibit NAFT?
This gives transplants greater success as the T cells will not attack the transplant
How does length of time that cells are bound change the outcome of a response?
Can change gene expression and differentiation of T cells from naive T cells.
What is the purpose of transduction in T cells?
To amplify the response
Why is IL-2 important in terms of T cell responses?
It can feedback on T cells and cause them to proliferate.
