W4.2

Question 1

T cell review

Answer 1

”- CD3

-each T cell expresses a unique TCR that recognizes a specific peptide antigen in the context of an MHC molecule

Question 2

T Cell - APC Interations

Question 3

Compare Endogenous/Exogenous pathway

Answer 3

“Endo - Class 1 MHC, CD8+, target cell

Exo - Class 2 MHC, CD4+. expressing APC “

Question 4

T cell differentiation

Answer 4

“60-80% of circulating lymphocytes in the peripheral blood = T cells

• differentiate in the Thymus
• Thymocyte = lymphocyte precursors, enter thymus from bone marrow
• maturation takes 3 weeks, from cortex to medulla “

Question 5

T cell receptor recombination

Answer 5

”- cells need to rearrange DNA to produce functionally expressed receptor chains
- 1/3 cells form a usefull receptor gene
germline DNA -> recombination -> rearranged DNA -> transcription splicing translation -> protein (T cell receptor) “

Question 6

importance of T cell maturation and positive/negative selection

Answer 6

keeps T cells that recognize autologous peptides from attacking self peptides/cells even though the TCR is randomly generated and can potentialy react with amost any peptide

Question 7

Thymus

Answer 7

“located above the heart, where naive T cells develop

- fully developed at birth, shrinks after puberty “

Question 8

Thymic stromal cells

Answer 8

include epithelial cells, macrophages, fibroblasts, and dendritic cells (play a role in T cell development)

Question 9

General steps of T cell selection

Answer 9

”- Random expression of alpha/beta TCR repertoire

• positive selection (exposure to MHC molecule)
• negative selection (exposure to self antigen)
• mature T cell pool “

Question 10

What is positive selection

Question 11

What is Negative selection

Question 12

What happens biologically when cells are weeded out of T cell selection

Answer 12

“Selection processes or failure to undergo productive rearrangements of antigen receptor genes
(less than 5% of thymocytes leace the thymus as naive T cells) “

Question 13

what is the importance of MHC to T cell development

Question 14

Naive T cells

Question 15

Resting memory cells

Question 16

Key steps in T cell responses

Answer 16

"1 - Antigen recognition 
2 - Lymphocyte activation 
3 - Clonal expansion 
4 - Differentation 
5 - Effector functions "

Question 17

IL-2 in T cell responses

Answer 17

induces T cell proliferation

Question 18

CD25 in T cell responses

Answer 18

When Tcells receive TCR: aMHC + costimulation they start to express CD25

Question 19

Clonal Expansion