TCR’s and BCR’s.

Question 1

What is the function of TCR’s and BCR’s?

Answer 1

They help B and T cells to recognise antigens.

Question 2

What part of a TCR or BCR binds to the epitope of an antigen?

Answer 2

The antigen binding component.

Question 3

What area of a B or TCR undergoes gene rearrangement?

Answer 3

The antigen binding component.

Question 4

Why is it important that the antigen binding component can under go gene rearrangement?

Answer 4

As if the genes were pre-destined the genome would be enormous.

Question 5

What part of a BCR or TCR never undergoes gene rearrangement?

Answer 5

The signalling component.

Question 6

What is the signalling component of a BCR or TCR involved in?

Answer 6

Signal transduction.

Question 7

What molecule within a TCR helps with signalling?

Answer 7

CD-3.

Question 8

What molecule within a BCR helps with signalling?

Answer 8

CD-79.

Question 9

What is the affinity of a BCR or a TCR?

Answer 9

How strongly it binds to an antigen.

Question 10

Will there be an immune response if a TCR or BCR binds weakly to an antigen?

Answer 10

No.

Question 11

What are the binding sites of BCRs and TCRs specific for?

Answer 11

Different antigens.

Question 12

Can TCRs and BCRs bind to different antigens?

Answer 12

Yes, this is how cross reactivity occurs.

Question 13

What must occur for an antigen to bind to a TCR?

Answer 13

It must be presented by an MHC-1 or MHC-2.

Question 14

What kind of peptides are read by TCR’s?

Answer 14

Only linear peptides.

Question 15

Are TCR’s ever secreted?

Answer 15

No, as they are membrane bound proteins.

Question 16

Can BCRs or TCRs bind to free antigens?

Answer 16

Only BCRs.

Question 17

Are BCR’s ever secreted?

Answer 17

They can be secreted as an antibody which is a BCR without the membrane anchor.

Question 18

Antibodies are always identical to what?

Answer 18

To the BCR on the B cell that made them.

Question 19

Can BCRs and TCR bind to multiple antigens?

Answer 19

No, they can only respond to one antigen at a time.

Question 20

Can BCRs and TCR recognise multiple antigens?

Answer 20

Yes.

Question 21

Why can BCRs and TCRs recognise so many receptors?

Answer 21

Because of gene rearrangement.

Question 22

What is the difference in antigen binding between BCRs/TCR’s and MHC molecules?

Answer 22

BCRs and TCRs can only bind to a single peptide.

MHC molecules can bind to multiple peptides.

Question 23

Why are there more B and T cells in the body than MHC molecules?

Answer 23

Because B and T cells are more specific and we need multiple B and T cells to recognise pathogens.

MHC molecules can bind to multiple antigens so 1 MHC can do the work of many B and T cells.

Question 24

Is the somatic gene rearrangement that occurs in TCRs and BCRs completely random?

Answer 24

Yes, this generates B cells and T cells that have billions of different receptors.

Question 25

What proteins are essential in the gene rearrangement that occurs in BCRs and TCRs?

Answer 25

RAG proteins.

Question 26

What are the co-stimulatory molecules that are found on the surfaces of T and B cells?

Answer 26

Additional receptors that are used for B and T cell activation. They are also used for immunophenotyping lymphocytes.

Question 27

What 2 cell types have antigen receptors?

Answer 27

B cells. T cells.

Question 28

What 3 cell types have antibody receptors?

Answer 28

Natural killer cell. Macrophages. Neutrophils.

Question 29

What stimulates the co-stimulatory molecules on BCRs and TCRs?

Answer 29

Exposure to PAMPs or cytokines.

Question 30

Are cytokines part of the innate or adaptive immune system?

Answer 30

The innate immune system.

Question 31

Are co-stimulatory molecules necessary for full B or T cell activation?

Answer 31

Yes.

Question 32

What happens when co-stimulatory molecules are activated?

Answer 32

They send a second signal which prevents an overreaction of the immune system.

Question 33

What do the co-stimulatory molecules on B and T cells help to prevent?

Answer 33

Autoimmunity and reactions to benign antigens such as food antigens.