Lecture 8: Development of T Lymphocytes Flashcards Preview

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Flashcards in Lecture 8: Development of T Lymphocytes Deck (94)
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1

HSCs home to the thymus and develop into 1 of 4 cells. What are those 4?

1) T helper (CD4)
2) Cytotoxic (CD8)
3) Natural Killer T (NKT)
4) T regulatory (Treg)

2

Where is the thymus located?

Superior to the heart, in between the lungs

3

When does the thymus begin to produce T cells?

around 12-13 weeks of gestation

4

True or False: by the time the baby is born, the peripheral T cell repertoire is established to the point that thymectomy does not cause immediate immune deficiency

TRUE (mature T cells can leave the thymus and colonize peripheral lymphoid organs at the end of 13 weeks of gestation)

5

The thymus is what kind of organ?

epithelial-lymphoid

(epithelial component develops from 3rd pharyngeal pouch bilaterally at 4 weeks of gestation)

6

When do HSCs first arrive to the thymus?

week 7-8 of gestation

7

What provides the genetic evidence for the thymus as the organ of thymopoiesis?

DiGeorge Syndrome or Velo-Cardio-Facial Syndrome (deletion of ch22q11)

Patients exhibit Athymia (undetectable T cells)
Thymus implants give rise to higher T cell numbers

8

What transcription factor is absolutely essential for T cell maturation/the thymus?

FOXN1

(mutations in it insert stop codon leading to no hair or no thymus)

9

Mature T cells stain _________ and are located in the thymic _________

lighter; medulla

10

Immature T cells are located in the ___________

cortex

11

What 2 cell types are found in the thymic stroma?

1) fibroblasts
2) epithelial cells

12

What cell types are found in the lymphoid compartment of the thymus?

HSCS, thymocytes, mature T cells, natural killer T cells, Tregs

13

From which germ layer do thymic epithelial cells derive?

endoderm

14

What transcription factor is essential for functional maturation of TECs?

Foxn1

15

What is one important function of TECs?

make cytokines required for T cell development (IL7, SCR, IL1, IL6, IL15)

16

How do T cells communicate in the thymus?

via Notch/Delta signaling

17

What is the cell surface ligand (for Notch receptor) on T cells?

Delta-Like 1,4

18

What effect of does insulin have on T cells of the thymus?

kills them when they interact with insulin

19

Where are macrophages and DCs located in the thymus?

cortex and medulla

20

Deletion of autoreactive T cells is accomplished in a process called

negative selection (accomplished by macrophages?)

21

Deletion of autoreactive T cells is accomplished in a process called

negative selection (accomplished by macrophages?)

22

What is the marker for HSCs in the thymus? How abundant are they?

CD34 (

23

The majority of the cells in the thymus are positive for which cluster differentiations?

CD4 and CD8 (double positives)

24

Of the mature T cells in the thymus, what percent are CD4? CD8?

10% CD4
5% CD8

25

What percentage of T cells are double negative for CD4 and CD8?

5%

26

What percentage of T cells are double negative for CD4 and CD8?

5%

27

As we age, daily production of T cells by thymus __________ (increases/decreases)

decreases

28

What are the 4 important developmental evens in the generation of mature T cells?

1) T lineage commitment: once they are in thymus, options are limited to T cell lineage
2) Proliferation: (expansion)
3) Differentiation: (gain new surface markers)
4) Maturation: (selection and gaining of immune functions)

29

What is the hallmark of a pre-T cell?

expression of CD1

30

What is the immature single positive stage of T cells?

When they go from being just CD1+ to CD4+ as well

(precursor for both TCRab and TCRyd T cells)