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Immunology > T Cell Development > Flashcards

Flashcards in T Cell Development Deck (28):
1

What is CD3?

Nonvariable subunits within TCR

2

What is DiGeorges syndrome?

genetic immunodeficiency in which there is a failure to develop thymic epithelium (no T lineage cells)

3

What is a nude mouse?

defect due to loss of transcription factor involved in thymic epithelial cell differentiation

4

What is thymic involution?

decreased output of thymus as you get older

5

Where do cells that seed the thymus come from and enter?

Prothymocytes from fetal liver and BM enter the thymus via blood vessels at the cortico-medullary junction

6

What produces chemotactic factors that attract T cell progenitors?

thymic anlage/rudiment

7

What controls thymocyte egress from the thymus? Where do they leave from?

-controlled by chemokines and sphingosine 1-phosphate receptors (lipid chemoattractant)
-leave from venules in medulla

8

What is central tolerance?

tolerance to self-antigens that is established in the T cells developing in the central or primary lymphoid organs (thymus and BM)

9

What is clonal deletion? What is it the main mechanism of? What is another name for it?

-elimination of immature T cells when they bind self-Ag
-central tolerance
-negative selection

10

What is positive selection?

only T cells whose receptors can recognize ag presented by self-MHC can mature

11

What rearrangments occur at DN stage?

TCR beta, gamma, and delta

12

What stage does TCR alpha rearrangement occur at?

double positive

13

What stage does positive and negative selection occur at?

double positive, after alpha rearrangment

14

Which are the most mature T cells?

single positive cells, high levels of CD3 and TCRbeta

15

What is the ratio of CD4 to CD8 cells?

2:1

16

What are the single positive cells that have low levels of CD3 and TCR beta?

immature single positives, in transition between double negative and double positive

17

What is the first check point in T cell development?

beta selection
-assesses whether TCR beta chain is functionally rearranged
-proliferates, expresses DP, terminates gamma locus, and initiates alpha locus

18

Will a double positive thymocyte ever express alpha-beta, and gamma-delta?

No, once you rearrange one there is no reason to rearrange the other

19

What is the second check point in T cell development?

positive and negative selection
-assesses whether TCR alpha is functionally rearranged and whether TCR is self-MHC restricted or auto-reactive
-DP goes to single positive with high TCR alpha levels

20

What is death by neglect?

absence of interaction with DP thymocytes causes apoptosis since they need signal to survive

21

If you knockout RAG, what stage are T cells stopped at?

double negative

22

If you knockout B2 microglobulin, what cell type do you not make?

CD8

23

What important process is mediated by AIRE?

-tissue-specific Ag from other parts of the body (peripheral Ag) are expressed in thymic epithelial cells in the medulla so T cells that respond to them can be destroyed

24

Where does positive selection occur?

cortex of the thymus

25

Where does negative selection occur?

cortex or medulla, but likely to concentrate at cortico-medullary junction and in medulla

26

What cells can induce negative selection?

thymic dendritic cells, cortical epithelial cells, medullary epithelial cells

27

What cell can't induce negative selection? What is its function?

thymic macrophages, its job is to eat the apoptosed cells

28

What must be upregulated to pass from cortex to the medulla?

TCR levels, positively selected