T Cell Development Flashcards
Why does a T cell become a T cell
No pax 5 gene. It leaves the bone marrow to thymus before rearrangement
What are T cell precursors called that go to thymus
Thumocytes
Give an example of a gene which starts tcr b rearrangement in thymus via rag expression
Notch gene
What makes up a pre T cell receptor
The rearranged tcr b via notch gene with a non variant pre tcr a
When can tcr a rearrangement start
After checkpoint with pre T cell receptor which is a tcr b rearranged and pre tcr a
What is acquired after tcr a rearrangement
Cd3,4 and 8 (double positive thymocytes)
What kind of selection occurs in the cortex of thymus by double positive thymocytes
Positive selection via self MHC recognition on cortical epithelial cells
Those that don’t recognise self MHC die because useless
How do double thymocytes get signals to say they’ve recognised self MHC and peptide in positive cortical selection
Cd3 and zeta chain dimer phosphorylation of ITAMS
What cells in medulla allow for negative selection of T cells which are self reactive to antigens (clonally deleted)
Apc like macrophages, dendrites
If there is too high affinity for MHC in positive selection in cortex. What does this mean
T cell is likely to be self reactive to ag so they are clonally deleted
Do y delta T cells have CD4/CD8 and become double positive Thymocytes
No. They will leave the thymus quickly to go to mucosal surfaces
When do T cells become single positive for CD4 or CD8
When they passed positive selection in cortex and negative selection in the medulla
