2.6 - Development of T cells

Question 1

Function of primary lymphoid organs

Answer 1

Maturation of immature cells (lymphoid stem cells) into immunocompetent lymphocytes

Question 2

Role of thymus

Answer 2

Maturation of thymocytes into T lymphocytes (T cells)

Question 3

Precursor T cells are derived from the ___ stem cell in the bone marrow and travel to the ___

Answer 3

Hematopoietic
Thymus

Question 4

Once T cells are mature, where do they go?

Answer 4

To secondary lymphoid organs like the spleen, lymph node, and gastro associated lymphoid tissue (GALT)

Question 5

What are the 2 portions of the thymus?

Answer 5

Cortical and medullary

Question 6

What cell types is the cortex made of?

Answer 6

Cortical epithelial cell
Thymocyte

Question 7

cortical epithelial cell origin

Answer 7

Thymic origin

Question 8

Thymocyte origin

Answer 8

Bone marrow

Question 9

Cell types of the medulla

Answer 9

Medullary epithelial cell
Macrophage
Dendritic cell

Question 10

Macrophage origin

Answer 10

Bone marrow

Question 11

Dendritic cell origin

Answer 11

Bone marrow

Question 12

When progenitor lymphoid cells come into contact w/ thymus, they enter around the ___ region and go up into the ___

Answer 12

Medullary cortical
Cortex

Question 13

As T cells develop, they go from ___ to ___ region

Answer 13

Cortex to medullary

Question 14

At birth the thymus is ___

Answer 14

Fully developed

Question 15

Thymus is replaced by fatty material as you get older. This is called

Answer 15

Involution

Question 16

Does loss of thymus mean loss of cell mediated immunity (CMI)?

Answer 16

No
Long living T cells and some self-renewal

Question 17

When the uncommitted progenitor cell from the bone marrow comes into contact with the thymic epithelium it gives rise to ___

Answer 17

double negative cells (CD4 and CD8)

Question 18

Marker for uncommitted progenitor cell?

Answer 18

CD34

Question 19

CD34 marker is important for bone marrow

Answer 19

Transplantation

Question 20

When cell becomes committed to being a T cell, it loses ___ expression and expresses T cells associated with ___ marker

Answer 20

CD34
CD2

Question 21

CD34 is a ___ surface marker

Answer 21

stem-cell

Question 22

CD2 is involved in

Answer 22

adhesion and signaling

Question 23

Are CD4 and CD8 active or inactive in double negative thymocyte committed to T cell lineage

Answer 23

Inactive

Question 24

TCR genes begin to ___ when the double-neg thymocyte committed to the T cell lineage

Answer 24

Rearrange

Question 25

Thymocyte expresses a receptor called ___

Answer 25

Notch 1

Question 26

Where is Notch 1 located

Answer 26

Thymic epithelium cells

Question 27

Describe notch 1

Answer 27

Driving force in thymic epithelium where thymocytes can be driven to become mature T lymphocytes

Question 28

When notch ligand’s attached it drives T cell towards ___

Answer 28

development

Question 29

What committed steps leave the thymus?

Answer 29

Committed gamma:delta T cell from beta, gamma, delta rearrangement
Committed gamma:delta T cell from alpha, gamma, delta rearrangement

Question 30

What is the result of beta, gamma, delta rearrangement

Answer 30

Committed gamma:delta T cell and committed double positive thymocyte are produced

Question 31

What does an uncommitted double positive thymocyte consist of?

Answer 31

CD8, CD4, and beta chain

Question 32

What is the result from alpha, gamma, delta rearrangement?

Answer 32

Committed gamma:delta T cell and committed alpha:beta T cell

Question 33

Majority of T cells are ___

Answer 33

committed alpha:beta T cell

Question 34

During rearrangement T cells are committed w/ gamma:delta T cell receptor or an uncommitted double positive thymocyte. Both will be ___

Answer 34

CD3+

Question 35

Both gamma:delta and alpha:beta T cells express

Answer 35

CD3

Question 36

An antibody to CD3 is used in supressing and removing T cells in patients undergoing a

Answer 36

Graft rejection

Question 37

In the blood over ___ of the circulating T cells express the alpha:beta receptor

Answer 37

90%

Question 38

T cells expressing the gamma:delta receptor are mainly located in the

Answer 38

epithelium surfaces including mucosal surfaces

Question 39

Where are the 2 check points for TCR?

Answer 39

After rearrangement of beta genes
After rearrangement of alpha genes

Question 40

If you can’t rearrange beta or gamma: delta at the checkpoint for pre-TCR, and you can’t rearrange alpha or gamma:delta at the checkpoint for TCR, what happens?

Answer 40

Cell dies

Question 41

RAG-1 and RAG-2 function

Answer 41

lymphoid specific recombinase

Question 42

TdT function

Answer 42

N-nucleotide addition

Question 43

CD3 and CD2 function

Answer 43

signal transducation

Question 44

Where can you find dead cells?

Answer 44

Cortex and cortex medullary region

Question 45

Describe positive selection

Answer 45

Stimulation of T cells that recognize correct MHC marker and elimination of those that don’t

Question 46

What happens if TCR interacts with MHC 1?

Answer 46

CD4 dies and end up with CD8 T cell

Question 47

What happens if TCR recognizes MHC II?

Answer 47

CD8 dies and end up with CD4 T cell

Question 48

Describe negative selection

Answer 48

Removal of T cells that bind and recognize self antigens that are associated with MHC

Question 49

Negative selection depends on ___ that express self antigens that come from thymus in blood

Answer 49

APC (dendritic cells and macrophages)

Question 50

Define peripheral tolerance

Answer 50

• Occurs after mature naive T cells leave the thymus
• occurs in peripheral blood or organs associated with

Question 51

What are the antigen presenting cells for positive selection?

Answer 51

Cortical epithelial cells
- Thymically derived

Question 52

What are the antigen presenting cells for negative selection?

Answer 52

Dendritic cells and macrophages
- Derived from bone marrow

Question 53

T cells that leave the thymus are known as ___

Answer 53

Mature naive T cells