2.1.6 development of T-lymphocytes

Question 1

______ stem cells can differentiate into all possible cell types

Answer 1

Totipotent

Question 2

______ stem cells have the ability to differentiate into almost all cell types, but lack the capacity to contribute extraembryonic tissue

Answer 2

Pluripotent

Question 3

____ stem cells have the potential to give rise to cells from multiple, but a limited number of lineages. an example of this is a mesenchymal stem cell or a _____

Answer 3

Multipotent, Hematopoietic stem cell

Question 4

The ____ is a primary lymphoid organ that plays a role in maturation of thymocytes into ______

Answer 4

thymus
T-lymphocytes

Question 5

The _____ is where B-cells mature

Answer 5

bone marrow

Question 6

Precursor T-cells are derived from the ______ stem cell in the _____ and travel to the _____

Answer 6

Hematopoetic stem cell
Bone marrow
thymus

Question 7

if a cell stays in the bone marrow to mature it becomes a _______

Answer 7

B-cell

Question 8

In the ______ area of the thymus, thymocytes are tightly packed and have a large cell turnover

Answer 8

Cortical

Question 9

As thymocytes mature in the thymus, they migrate to the ____ portion

Answer 9

medullary

Question 10

Progenitor lymphocyte cells enter the thymus around the ______ and then go up into the ______

Answer 10

Medullary cortical region
cortex

Question 11

what are the two types of cells in the cortex we need to know? Where do they originate?

Answer 11

1. cortical epithelial cell
   - thymus
2. thymocyte
   - bone marrow

Question 12

what are the two types of cells in the medulla we need to know? Where do they originate?

Answer 12

1. Dendritic cell
   - bone marrow
2. macrophage
   - bone marrow

Question 13

_______ can be found in both the cortex and medullary region

Answer 13

thymocytes

Question 14

When is the thymus fully developed?

Answer 14

birth, after this it experiences Involution and degenerates

Question 15

the thymus is replaced by what kind of material during involution?

Answer 15

Fatty material

Question 16

which of these thymus would you expect to belong to an infant? which would belong to an elderly person?

Answer 16

A- infant, not very involuted
B- elderly, very degenerated

Question 17

when the uncommitted progenitor cell from the bone marrow comes in contact with the thymic epithelium it gives rise to ________. what does this mean?

Answer 17

Double negatives
- it is CD4/CD8 negative

Question 18

______ is the marker of immaturity/ an uncommitted progenitor

Answer 18

CD34

Question 19

when does a cell lose the CD34 expression?

Answer 19

when it becomes committed to become a T-cell

Question 20

what do double negative T-cells express?

Answer 20

CD2

Question 21

Thymocyte expresses a receptor called ______ which is activated when it interacts with the ____ ligand on the thymic epithelium

Answer 21

Notch1
Notch ligand

Question 22

what does the Notch 1 receptor do once activated?

Answer 22

drives T cell towards T cell development

Question 23

How does an uncommitted progenitor give rise to alpha/beta and gamma/delta cells?

Answer 23

1. Uncommitted progenitor → committed double negative T-cell progenitor
2. T-cell progenitor now goes through Beta or Gamma/Delta rearrangements
3. Gamma/delta cells leave thymus
4. Uncommitted double-positive thymocyte with Beta (has CD8 and CD4) goes through another set of rearrangements: either alpha OR gamma delta
5. gamma/delta cell will leave and go to thymus
6. now theres also a committed alpha/beta cell (majority)

Question 24

which rearrangement do most cells go through? Beta or delta/gamma?

Answer 24

Beta, its easier to just rearrange one

Question 25

the majority of T-cells are _____

Answer 25

alpha/beta

Question 26

Both alpha/beta and delta/gamma express ______

Answer 26

CD3

Question 27

When can an antibody to CD3 be used?

Answer 27

in suppressing and removing T cells in a patient who is undergoing a graft rejection

Question 28

Where are gamma/delta t-cells found?

Answer 28

epithelium surfaces including mucosal surfaces

Question 29

where are the two TCR checkpoints?

Answer 29

1. during the first rearrangement (if neither gamma/delta or Beta rearrange, the cell will die
2. second rearrangement (if cant rearrange gamma/delta or alpha, cell will die)

Question 30

what do CD3 and CD2 function in?

Answer 30

signal transduction

Question 31

why is there significant cell death in the cortical area?

Answer 31

positive and negative selection

Question 32

______ selection is when the T-cell receptor is removed if it doesn’t recognize the appropriate MHC

Answer 32

Positive

Question 33

_______ selection is when self-recognizing t-cells are removed

Answer 33

negative

Question 34

how do T-cells become either CD4 or CD8 positive?

Answer 34

if the TCR interacts with MHC1, CD4 is lost (will be CD8)

if TCR interacts with MHC2, CD8 is lost (will be CD4)

Question 35

_____ tolerance is negative selection in the thymus, while _____ tolerance is negative selection in self-reacting cells that leave the thymus

Answer 35

Central

Peripheral

Question 36

what are the APCs for positive selection?

Answer 36

cortical epithelial cells (thymically derived)

Question 37

what are the APCs for negative selection?

Answer 37

dendrites, macrophages (bone marrow derived)