The development of T lymphocytes

Question 1

where do T cells develop (start off with an easy one ;) )

Answer 1

thymus

Question 2

as we age does the thymus degrade

Answer 2

yes

Question 3

do thymocytes commit to the T cell lineage before rearranging their T cell receptor genes

Answer 3

yes

Question 4

how long does it take with interaction of thymic stomal cells for them to become thymocytes

Answer 4

1 week

Question 5

what do double negative cells mean

Answer 5

we dont know if they will be helpful or cytotoxic T cells (CD8 and CD4)

Question 6

does the RAG complex become activated when the uncommitted progenitor cell turns into a double negative thymocyte committed to the T cell lineage

Answer 6

yes

Question 7

does the CD34 stay positive when the uncommitted progenitor cell turns into a double negative thymocyte committed to the T cell lineage

Answer 7

no it becomes negative

Question 8

does Notch signaling drive T cell development

Answer 8

yes

Question 9

notch signaling pathway

Answer 9

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

Question 10

which genes start at the beginning of T cell lineages

Answer 10

gamma, delta and beta genes start racing

Question 11

what happens if the beta chain recombines first

Answer 11

you have an uncommitted double negative thymocyte

Question 12

what happens with the uncommitted double negative thymocyte from the beta chain recombining

Answer 12

another race happens where alpha takes over betas place

Question 13

what happens if alpha gene wins the race

Answer 13

the cell becomes and committed alpha-beta T cell which is functional and expresses CD8 and CD4 receptors

Question 14

what happens if gamma and delta rearrange the cell first

Answer 14

the T cell will move on as a gamma-delta T cell receptor

Question 15

what percentage of thymocytes are successful and then which cells clean up after them

Answer 15

2%, macrophages

Question 16

what does VDJ rearrangement result in

Answer 16

beta and delta genes

Question 17

what does VJ rearrangement result in

Answer 17

alpha and gamma genes

Question 18

what is the developmental pathway determined by

Answer 18

which can make productive rearrangements, get to the cell surface and start signalling

Question 19

why does the beta chain normally win?

Answer 19

rearranging 1 chain is easier than rearranging 2 (gamma and delta)

Question 20

when does rearrangement of the alpha chain occur

Answer 20

in pre-T cells

Question 21

do all the beta chains look the same because of allelic exclusion?

Answer 21

yes

Question 22

do the alpha chains all look different and why

Answer 22

they all look different which allows for diversity in the cells

Question 23

what does CD4 and CD8 expression induce

Answer 23

double positive thymocytes

Question 24

how many checkpoints are there during early T cell development

Answer 24

2

Question 25

what happens when T cells recognize self-MHC molecules in the thymus

Answer 25

theyre positively selected

Question 26

when there is moderate or strong binding the positive thymocyte binds to MHC molecules and lives: T or F

Answer 26

true

Question 27

what happens when there is weak binding between the negative thymocyte and the MHC molecules

Answer 27

they die

Question 28

what does positive selection determine

Answer 28

the expression of either the CD4 or the CD8 co-receptor

Question 29

what happens when T cells recognize self antigens in the thymus

Answer 29

they are removed by negative selection

Question 30

what is the function of negative selection of thymocytes in the thymus

Answer 30

to eliminate autoreactive thymocytes

Question 31

when there is tight binding between a negative thymocyte to the MHC molecules what happens

Answer 31

the cell dies

Question 32

when there is moderate binding between a positive thymocyte to the MHC molecules what happens

Answer 32

cell lives