T cells

Question 1

When can T cells recognise protein antigens?

Answer 1

Only after they are broken down into peptide fragments

Question 2

How are T cells presented with peptides?

Answer 2

the MHC class 1 molecules

Question 3

What receptors do T cells express on their surface?

Answer 3

• T cell receptor (TCR)
• Either a CD8 or CD4 receptor

Question 4

Where is MHC class 1 found?

Answer 4

On the surface of most nucleated cells

Question 5

What type of T cells express the CD8 receptor on their surface?

Answer 5

Cytotoxic T cells

Question 6

What is the function of CD4 T cells?

Answer 6

They help other innate and adaptive immune cells to execute their effector function (‘helper T cells’)

Question 7

Which MHC class do CD8 T cells respond to?

Answer 7

Class 1

Question 8

Which MHC class do CD4 T cells respond to?

Answer 8

Class 2

Question 9

Where is MHC class II found?

Question 10

How many chains are T cell receptors made up of?

Answer 10

8

Question 11

What is the function of the alpha and beta chains of T cell receptors?

Answer 11

They mediate antigen recognition

Question 12

What are MHCs?

Answer 12

Glycoproteins which display peptides on the surface of T cells

Question 13

How many gene loci are there for where MHC 1 are expressed?

Answer 13

3

Question 14

How many different MHC class 1 are on each cell?

Answer 14

6

Question 15

What type of proteins are processed and presented with MHC class 1 molecules?

Answer 15

Cytosolic proteins

Question 16

Outline how MHC class 1 presents proteins

Answer 16

• cytosolic proteins are processed to peptides in proteasome
• Peptides bind to MHC class 1 molecules in the ER
• The MHC class 1 molecules are transported through the Golgi apparatus and trafficked to the surface

Question 17

What are the characteristics of MHC Class 1?

Answer 17

• One heavy chain
• Associated with beta-2 microglobulin
• Peptide short

Question 18

What type of proteins do MHC Class II molecules present?

Answer 18

Extracellular proteins

Question 19

Outline how MHC Class II presents proteins

Answer 19

• Proteins are taken into endocytic vesicles
• The proteins are then digested to peptides in the endosomes
• Vesciles containing MHC Class II fuse with the endosomes and then resulting molecules are moved to the surface of the cell

Question 20

What are the characteristics of MHC Class II?

Answer 20

• 2 heavy chains
• binds longer peptides than class 1

Question 21

Where are T cells produced?

Answer 21

In the bone marrow

Question 22

Where are T cells educated?

Answer 22

The thymus

Question 23

What type of cells activate T cells?

Answer 23

Dendritic cells

Question 24

How many types of CD4 T cells are there?

Answer 24

3

Question 25

What are the 3 groups of CD4 T cells?

Answer 25

* Th1 * Th2 * Th17

Question 26

What is the function of T_FH cells?

Answer 26

They enhance B cell differentiation in germinal centres

Question 27

What are the types of CD4 T cell?

Answer 27

* Helper * Follicular helper * Regulatory

Question 28

What is the main function of CD4 regulatory T cells?

Answer 28

They supress the immune response to prevent inappropriate response to self

Question 29

What is the function of Th1 cells?

Answer 29

* Help macrophages respond to intravesicular pathogens by producing cytokines

Question 30

What costimulatory molecules do dendritic cells produce that activate T cells?

Answer 30

CD80 and CD86

Question 31

What effects does an activated macrophage have?

Answer 31

* Increases production of oxygen radicals * Increases intracellular killing * Increases production of cytokines to drive inflammation * Recruits other immune cells

Question 32

How can macrophages provide feedback communication?

Answer 32

Peptides from the degradation of bacteria can be presented on MHC class II molecules

Question 33

How do Th1 and Th2 cells help B cells to produce antibodies?

Answer 33

They stimulate isotype swtching

Question 34

Explain the role of dual recognition in activation of B cells?

Answer 34

* 2 recgonition events must occur independently in order to activate b cells * Helps to prevent self-recognition

Question 35

What recognition events must occur to activate a B cell?

Answer 35

* CD4 T cellhas to recognise an antigenic peptide * B cell needs engagement of the B cell receptor

Question 36

How do T_FH help activate B cells?

Answer 36

They promote the formation of germinal centres

Question 37

What is the function of CD8 T cells?

Answer 37

They are cytotoxic T cells which kill tumour cells or cells infected by cytosolic pathogens

Question 38

What do CD8 T cells secrete as a pro-inflammatory cytokine?

Answer 38

IFNγ

Question 39

What cytotoxic proteins do CD8 T cells produce?

Answer 39

* Perforin * Granzymes * Granulysin

Question 40

How do CD8 T cells release cytotoxic proteins?

Answer 40

* Recognition of a target cell occurs * Cytotoxic granules move and become polarised * The granules are then released at the site of cell contact