L3.2 T cell production

Question 1

where are progenitors for T cells produced

Answer 1

in the bone marrow the migrates to the thymus

Question 2

where are the t cells produced

Answer 2

in the thymus

Question 3

structure of the thymus gland

Answer 3

medulla and cortex, lined with fat

Question 4

what sturctures of thymus changes with age

Answer 4

as the age increases, size of the coretx and medulla decreases while the fat mass increases
- this decrease T cell production

Question 5

thymus consists of two cellular elements

Answer 5

haemopoietic - percursors that develop into T cells

stromal cells - drive development T cell precurors

Question 6

epitheliums in the thymus

Answer 6

subcapsular, cortical and medullary

Question 7

stages of T cells

Answer 7

1st - t cell DN, no CD4 and no CD8
2nd - becomes DP
3rd- eith become CD4 single positive or CD8 single positive

• as the stages progresses, the T cells becomes more mature

Question 8

two main checkpoitns in the T cell development

Answer 8

1st - maturation from DN to DP stage

2nd - maturation from DP to SPCD4 or SPCD8 stage

Question 9

events taking place between the stages from DN to DP

Answer 9

• progenitor commiting to T cell lineage whilst preventing producing other cells
• proliferation of the early T cell precursors and expresisng receptors
• random rearrangement of T cell receptor genes

Question 10

what is pre T cell receptor complex

Answer 10

has TCR beta chains, CD3 complex and pre Talpha

• expressed on DN t cells only
• important in signalling to generate DP t cells

Question 11

two situations where rerrangemnt of the genes in the T cell can lead to

Answer 11

cell death if the rearrnagement is unsuccessfuk

or if successful, expresses CD4 AND CD8

Question 12

how can T cell recognise antigens

Answer 12

if presented by antigen presenting cell (MHC complex )

Question 13

how to select T cells

Answer 13

keep the useful - T cells can recognise MHC ofnlow affinity

• remove harmful - recognise high affinity
• remove useless if they dont recongise MHC
• keeping - the positive selection
  removing - neg selectio

Question 14

how to is CD4 SP T cell formed

Answer 14

if the CD4 interacts with the MHC class 2, the CD4 is passed onto the t cell from the epithelium from the progenitor

Question 15

how to is CD8 SP T cell formed

Answer 15

when the CD8 interacts with MHC class 1 on thymic epithelium, the CD8 is passed on from the progenitor