Lecture 3

Question 1

How are T cell receptors encoded?

Answer 1

By rearranging genes

Question 2

What regions of the T cell receptors are encoded?

Answer 2

Variable regions are encoded by V,D,J segments

Question 3

Where do b cells develop?

Answer 3

In the bone marrow

Question 4

Where to T cells go once they have left the bone marrow?

Answer 4

Thymus

Question 5

When do T cells rearrange?

Answer 5

When in the thymus, don’t turn on until they are in the thymus

Question 6

When do B cells rearrange?

Answer 6

When in the Bone marrow

Question 7

What are some similar mechanisms that are seen in in TCR that are also in BCR?

Answer 7

Multiple V,D and J gene segments, combinatorial diversity and junctional diversity

Question 8

Unlike a BCR what is never done in a TCR?

Answer 8

It is never secreted it is always found on the surface of the cell

Question 9

What else is not found in the T cell?

Answer 9

Hyper mutation

Question 10

What happens randomly in T cells?

Answer 10

An individual T cell will breaks its DNA randomly during the alpha D and V region

Question 11

What to alpha and beta chains do?

Answer 11

Pair up to combine together to make a unique T cell receptor in the cell

Question 12

What is T cell alpha chain similar to?

Answer 12

Light chain

Question 13

What is the T cell beta chain similar to?

Answer 13

Heavy chain

Question 14

Why do T cells not have hyper mutation?

Answer 14

Because the don’t contain AID (activation induced cytidine deaminase

Question 15

On the beta chain what binds first?

Answer 15

D and J chain then they combine with a v chain

Question 16

Where does splicing occur on a T cell?

Answer 16

Constant region

Question 17

Where do TCR recognise antigens?

Answer 17

In grooves of MHC molecules

Question 18

Where is the single alpha chain located?

Answer 18

On chromosome 14

Question 19

What will T cells generate?

Answer 19

Either alpha beta cell receptors or gamma delta cell receptors

Question 20

What are the gene segments found in a TCRbeta?

Answer 20

V,D,J,C

Question 21

What are the gene segments found on TCRalpha?

Answer 21

V,J,C

Question 22

Where is HLA found?

Answer 22

On chromosome 6

Question 23

How are MHC expressed?

Answer 23

Co-dominantly

Question 24

What do class I MHC molecules express?

Answer 24

All nucleated cells

Question 25

What do class II MHC molecules express?

Answer 25

Expressed on only particular cell types

Question 26

What are the specific types of cells that MHC class II molecules express?

Answer 26

B cells, macrophages, dendritic cells

Question 27

What are MHC molecules induced by?

Answer 27

Interferons (inflammation)

Question 28

How many MHC molecules will a single gene contain?

Answer 28

12 MHC molecules

Question 29

What is the gene structure of class I MHC molecules?

Answer 29

HLA-A, HLA-B, HLA-C

Question 30

What is the gene structure for class II MHC molecules?

Answer 30

HLA-DP, HLA-DQ, HLA-DR

Question 31

What do class II molecules contain?

Answer 31

Maternal and paternal expression

Question 32

If there is one heterozygous gene at each loci how many class I molecules can be expressed?

Answer 32

6 different class I molecules

Question 33

What is the co-dominant expression of MHC molecules?

Answer 33

Polymorphism and polygeny

Question 34

Where do polymorphism occur?

Answer 34

In clusters

Question 35

Where does the variability of MHC molecules occur?

Answer 35

Occur where the MHC forms the peptide binding groove

Question 36

What are regions for such high levels of MHC polymorphism?

Answer 36

Binding of a vast range of peptides that be presented to T cells

Question 37

What is the downside of high levels of MHC polymorphism?

Answer 37

Increased immune-mediated disease e.g. increases the likelihood of presenting self antigens (could state an immune response on yourself)

Question 38

Where are antigens from?

Answer 38

Either from inside the cell or from a pathogen that has hijacked a cell

Question 39

Endogenous?

Answer 39

Inside the cell - will end up on the source of the cells by class I

Question 40

Exogenous?

Answer 40

Outside the cell - bacteria that float around outside cells get taken up by the cells - MHC class II

Question 41

What do macrophages do?

Answer 41

They eat antigens and display them on its surface

Question 42

How do peptides end up on the surface of the cells bound to MHC molecules?

Answer 42

The are PROCESSED into small peptide fragments suitable for binding to and presentation by MHC I and II

Question 43

What does the proteasome do to antigens?

Answer 43

Degrade and chop up the antigens in the cytoplasm

Question 44

Where are class I molecules found?

Answer 44

In the ER

Question 45

What does the proteasome allow the fragments in the ER to do?

Answer 45

Bind to peptide binding grooves which allows class I molecules to go out of the ER into the cell surface

Question 46

Where is the viral protein synthesised in class I?

Answer 46

In the cytoplasm

Question 47

How are the peptides transported in class I?

Answer 47

By the TAP transporter - to ER

Question 48

What happens once the peptides bind to the class I molecules?

Answer 48

Transported to the cell surface

Question 49

What can the proteasome change?

Answer 49

Can change its behaviour depending on what happens outside the cell

Question 50

What is TAP TRANSPOTER?

Answer 50

A component of multi protein assembly

Question 51

What does the TAP component contain?

Answer 51

Contains tapasin and calreticulin

Question 52

Where is the bacteria (antigen) found in the MHC II molecule?

Answer 52

Endocytosed into intracellular vesicles inside the cell

Question 53

How is the protein cleaved to peptides in MHC II?

Answer 53

By acid proteases in vesicles

Question 54

Where is class II targeted?

Answer 54

Targeted in the endocydic pathway

Question 55

Why aren’t class II molecules loaded into the ER?

Answer 55

Because the invariant chains stops this from happening

Question 56

What does the invariant chain do?

Answer 56

Binds to the class II peptide binding groove blocking the peptides from getting into the ER

Question 57

What happens to the lysosomal enzymes in the endocydic pathways (MHC class II)

Answer 57

They get degraded leaving the CLIP peptide associated with the binding groove

Question 58

What can displace the CLIP?

Answer 58

Peptides from the antigen

Question 59

What is HLA-DM required for?

Answer 59

Loading peptides into the groove

Question 60

What happens in normal healthy uninfected cells?

Answer 60

MHC I and II will bind and present peptides from self proteins

Question 61

What are LMPs?

Answer 61

They are molecules part of the proteasome - change change the features of the proteasome

Question 62

What can class I molecules be killed by?

Answer 62

CD8+ (cytotoxic cells)

Question 63

What are MHC II cells also known as?

Answer 63

APC (antigen presenting cells)

Question 64

What are some example of antigen presenting cells?

Answer 64

Macrophages, dendritic cells and B cells

Question 65

What cells can express MHC class II cells?

Answer 65

CD4 T helper cells