lecture 35 - T cells

Question 1

Where do T cells arise?

Answer 1

Bone marrow

Question 2

How does the thymus develop a T cell to maturity?

Answer 2

TCR gene rearrangement

Question 3

What is the name for immature T cells, or other immune cells, that enter the thymus?

Answer 3

Thymocytes

Question 4

What occurs during thymus gene rearrangement?

Answer 4

Thymocytes rearrange the genes coding for the variable part of their TCR (T cell receptor)

Question 5

Why are a huge variety of TCR receptors expressed across the T cells leaving the thymus?

Answer 5

TCR gene rearrangement is essentially random, producing a wide array of receptors that may or may not be useful in identifying specific antigens

Question 6

What does a TCR recognise?

Answer 6

A specific peptide + MHC

Question 7

What are the 2 types of T cell co-receptor?

Answer 7

CD4 and CD8

Question 8

What is the function of a CD4 receptor?

Answer 8

Assists with the docking of the TCR onto MHC-II and peptide

Question 9

What MHC does the CD4 co receptor aid in the docking of?

Answer 9

MHC-II

Question 10

What is the function of the CD8 coreceptor?

Answer 10

Assists with the docking of the TCR onto specific peptides and MHC-I.

Question 11

What MHC does CD8 aid in the docking of?

Answer 11

MHC-I

Question 12

What is the name given to T cells that have not been activated by MHC/peptide?

Answer 12

naïve

Question 13

What is the name for activated T cells?

Answer 13

Effector T cells

Question 14

What are CD4 T helper cells?

Answer 14

T cells with CD4 coreceptors that recognise MHC-II and peptide from endogenous antigens. Activate B cells and release cytokines to activate CD8 T cells.

Question 15

What is the function of CD4 T helper cells?

Answer 15

Help CD8 T cells become cytoxic by producing cytokines. Help B cells make antibody

Question 16

What are CD8 cells?

Answer 16

T cells with CD8 co receptors that recognise MHC-I and peptides from exogenous antigens

Question 17

What do CD8 T cells develop into?

Answer 17

cytoxic T lymphocytes (CTL)

Question 18

What are CTLs (cytoxic T lymphocytes) derived from?

Answer 18

CD8 cells

Question 19

What is the function of CTL (cytoxic T lymphocytes)?

Answer 19

Targeted death (apoptosis) of infected cells so they can no longer act as hosts to pathogens, or so cancerous cells cannot further divide.

Question 20

What is apoptosis?

Answer 20

Orderly, targeted cell death by CTLs

Question 21

Why must target cell death be orderly?

Answer 21

Random cell lysis would lead to the spilling out of viruses from inside the diseased cell, allowing them to spread to and infect other cells.

Question 22

What are memory cells?

Answer 22

T cells that reside in the body for long periods of time until a relevant pathogen is detected, at which point they can rapidly form effector T cells.

Question 23

What are the two key types of memory T cells that reflect their potential function?

Answer 23

CD4 and CD8 memory T cells.

Question 24

Why does the body produce memory T cells?

Answer 24

To allow the adaptive immune response to kick in rapidly when a familiar threat is identified, rather than having to go through the slower process of turning naïve T cells into effector T cells.

Question 25

How are CTLs activated?

Answer 25

By cells that display peptides that match the CTL, as well as MHC-1