T Cell Development Flashcards
Where do the HSCs that go to the thymus to become T cells come from?
Bone marrow
Why does the removal of the thymus not cause immediate immune deficiency in infants?
Peripheral T cells pools are developed before birth
What are some effects of the mutation of the FOXN1 gene?
No hair and no thymus
What is on the HSC to communicate with the TECs?
Notch Receptor
What happens to T cells with age?
The number of T cells decreases
What event marks T cell commitment?
Notch receptor and Notch ligand Delta-Like 1 or 4 (DL-1, DL-4) interaction induces T lineage commitment and terminates lineage plasticity
What is positive TCR selection?
TCR must see Ag and the MHC before it becomes either CD4 or CD8 depending on the class of MHC that it binds. Cells that bind weakly will be eliminated.
What is negative TCR selection?
When TCR on a DP cell binds antigen/MHC with high affinity, it is signaled to undergo apoptosis. This is the basis for intrathymic negative selection and the establishment of central tolerance.
What is the main receptor found on the HSC cell triggering its function?
CD34
What converts a T/NK cell into a pre-T cell and what happens in the pre-T stage?
CD1A and it causes a rearrangement of the gamma, delta and beta.
What converts the pre-T into the ISP (immature singe positive) state?
CD4 converts it to the ISP where it will express preTα which leads to CD3 expression.
What is the preTCR complex and when does it form?
The preTα with CD3 and TCRβ will form the preTCR complex and this occurs during the ISP state.
What happens after the expression of the preTCR in the ISP state?
The cell will undergo β selection where functional TCRβ are selected for and nonfunctional ones are destroyed via apoptosis.
After the ISP passes β selection what happens to the ISP?
It will become a DP (double positive) cell via the expression of CD8 and begins to rearrange the TCRα which deletes the δ as a result and confirms the T cell for Tαβ
