T Cell Development, Receptor Repertoire Selection And CD4/8 Lineage Commitment Flashcards
What does CD stand for in CD4/8?
Cluster of differentiation
Where do double negative T cells appear?
In the foetus
What type of T cells are favoured during early foetal development?
Gamma delta T cells
Do gamma delta T cells recognise the MHC protein?
No
What do gamma delta T cells play a role in?
Cancer surveillance
What does T cell development involve?
The sequential generation, assembly and testing of the newly rearranged TCR
What does a double +ve thymocyte need to progress to the single +ve stage?
Functional TCR alpha chain rearrangement CD4 and MHC II (-> CD4+) CD8, MHC I and TAP (-> CD8+) ERK signalling Calcineurin signalling
What is the initiation process of apoptosis?
Interaction between FAS ligand and FAS -> reaction cascade -> caspase 8 -> caspase cascade -> cell death
What can happen to a double +ve thymocyte?
Bind to MHC II (-> CD4+)
Bind to MHC I (-> CD8+)
Death by neglect
Negative selection
What are MHCs called in humans?
Human leukocyte antigens
Where are MHC-IIs expressed?
Thymic medullary stromal cells and high levels on APCs
What happens if the binding is too strong to self T cells?
The cell is reprogrammed for apoptosis
What does negative selection of T cells ensure?
Self-reactive cells are removed
Why are self Tcells removed?
They may cause autoimmunity
What is negative selection determined by?
Affinity of TCR for presented self peptide
What does AIRE stand for?
Autoimmune regulator
What is AIRE?
A transcription activator gene that can induce expression of other tissue specific proteins
What is promiscuous gene expression?
Ectopic gene expression in the thymic medullary stroma
What may regulatory T cells develop in the thymus?
High expression of CD25 and Foxp3
What is the main role of regulatory T cells?
To dampen T cell response
