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Flashcards in T cell development Deck (32):
1

Epithelial component of the thymus

Develops bilaterally from the third pharyngeal pouch at 4 weeks gestation

2

When does the thymus split from the pharynx?

Between weeks 4 and 7

3

When is the thymus colonized with hematopoietic stem cells?

7th week

4

When does the thymus produce T cells?

12th week

5

When do T cells leave the thymus?

13th week

6

DiGeorge syndrome

Deletion in the 22nd chromosome; complete T cell deficiency and severe immunodeficiency

7

FOXN1 gene

On chromosome 17. Codes for a transcription factor necessary for maturation of T cells

8

Thymic epithelial cells

Produce cytokines important for growth and differentiation
Expresses notch receptors that are crucial for T cell lineage commitment
Expression of peripheral tissue antigens

9

Corticomedullary junction of the thymus

Where dendritic cells and macrophages reside for antigen presentation and phagocytosis of self-reactive T cells

10

What CD marker is present on the hematopoietic stem cells in the thymus?

CD34

11

Four developmental events in T cell maturation

T lineage commitment
Proliferation and differentiation
Selection
Maturation

12

Persistent Notch signaling

Commits T cells to the lineage; short signaling can cause NKT development OR T cell development

13

Notch ligands

DL-1 and DL-4

14

What happens once T cells commit to the lineage?

Express CD1, recombine delta, gamma, beta genes

15

What is required for recombination of T cells?

RAG-1 and RAG-2, as well as IL-7

16

How is recombination terminated?

Through ERK after signaling by preTCR

17

PreTCR is mediated by what?

CD3 with preT-alpha

18

Beta selection

Cell gets checked for a functional preTCR and if it works, then it massively proliferates; if it doesn't, it dies

19

What skews the T cells toward alpha-beta instead of gamma-delta?

The presence of pTalpha

20

Two dominant gamma-delta T cells

Delta-1 with various gamma genes
Gamma-9 delta-2

21

What do delta-1 T cell receptors do?

The first to emerge from the fetus
Colonize in epithelial cells
Recognize stressed cells and lipid signals presented by CD1B and CD1C

22

CD1 transmembrane proteins

Distantly related to MHC; there are four. A, B, C, and D

23

What do CD1B and CD1C associate with?

Beta-2 microglobulin

24

What do TCRgamma2delta9 cells do?

Recognize non-peptide phosphor antigens on mycobacterium and malaria, release IFNgama

25

What co-stimulant is required for development of NKT cells?

CD1D

26

What are the CDs expressed by NKT cells?

Either CD4 positive or double-negative, with CD56 and TCRalpha-beta/CD3 complex

27

What do NKT cells do?

Release Th1 and Th2 cytokines

28

Function of Treg cells

Help in the negative selection process

29

What is the selection process mediated by Treg cells called?

Dominant tolerance

30

CDs on Treg cells

CD4 and CD25

31

What signals for peripheral generation of Tregs?

TGF-beta

32

FOXP3

Necessary for the production of Tregs in the thymus