The development of T lymphocytes Flashcards
where do T cells develop (start off with an easy one ;) )
thymus
as we age does the thymus degrade
yes
do thymocytes commit to the T cell lineage before rearranging their T cell receptor genes
yes
how long does it take with interaction of thymic stomal cells for them to become thymocytes
1 week
what do double negative cells mean
we dont know if they will be helpful or cytotoxic T cells (CD8 and CD4)
does the RAG complex become activated when the uncommitted progenitor cell turns into a double negative thymocyte committed to the T cell lineage
yes
does the CD34 stay positive when the uncommitted progenitor cell turns into a double negative thymocyte committed to the T cell lineage
no it becomes negative
does Notch signaling drive T cell development
yes
notch signaling pathway
notch ligand binds to notch 1, bond between gets cut in the thymocyte, then travels into the nucleus in order to activate transcription of T cell development
which genes start at the beginning of T cell lineages
gamma, delta and beta genes start racing
what happens if the beta chain recombines first
you have an uncommitted double negative thymocyte
what happens with the uncommitted double negative thymocyte from the beta chain recombining
another race happens where alpha takes over betas place
what happens if alpha gene wins the race
the cell becomes and committed alpha-beta T cell which is functional and expresses CD8 and CD4 receptors
what happens if gamma and delta rearrange the cell first
the T cell will move on as a gamma-delta T cell receptor
what percentage of thymocytes are successful and then which cells clean up after them
2%, macrophages
what does VDJ rearrangement result in
beta and delta genes
what does VJ rearrangement result in
alpha and gamma genes
what is the developmental pathway determined by
which can make productive rearrangements, get to the cell surface and start signalling
why does the beta chain normally win?
rearranging 1 chain is easier than rearranging 2 (gamma and delta)
when does rearrangement of the alpha chain occur
in pre-T cells
do all the beta chains look the same because of allelic exclusion?
yes
do the alpha chains all look different and why
they all look different which allows for diversity in the cells
what does CD4 and CD8 expression induce
double positive thymocytes
how many checkpoints are there during early T cell development
2
