Major Histocompatibility Complex (MHC) and Antigen Processing and Presentation to αβ T Cells and Transplantation

Question 1

What molecules present antigen to the adaptive immune system?

Answer 1

MHC I and MHC II

Question 2

What molecules does the adaptive immune system use to recognize antigens?

Answer 2

B-cell receptor and T-cell receptor

Question 3

What is the immunoglobulin superfamily?

Answer 3

any molecule that has a basic domain structure; similar to the structure of antibody (110 amino acid domains)

Question 4

What are examples of molecules in the immunoglobulin superfamily?

Answer 4

CD4, bcr, trcm, cks

Question 5

What is the structure of MHC I?

Answer 5

long alpha chain, one transmembrane portion and a beta 2 microglobulin chain

Question 6

Where is MHC I located?

Answer 6

on all nucleated cells

Question 7

What T cell binds to MHC I?

Answer 7

CD8 - cytotoxic T cells

Question 8

Is MHC I endogenous or exogenous?

Answer 8

endogenous

Question 9

How many AA long is MHC I?

Answer 9

9

Question 10

Where is MHC II located?

Answer 10

on all antigen presenting cells; dendritic, macrophage, and memory b cells

Question 11

What is the structure of MHC II?

Answer 11

An alpha and beta chain both containing a transmembrane portion, and a peptide binding region

Question 12

What T cell binds to MHC II?

Answer 12

CD4 - t helper cell

Question 13

Is MHC II endogenous or exogenous?

Answer 13

exogenous

Question 14

What type of vaccine would follow the exogenous pathway?

Answer 14

killed vaccines

Question 15

What are the steps of the exogenous pathway (4)?

Answer 15

1. Dendritic cell breaks it up into peptides in a vesicle
2. Dendritic cell is creating an MHC 2 molecules with an invarient chain blocking the groove
3. When the vescicle fuses with a lysosome, the invarient chain is removed which allows peptides to be bound to the MHC 2 molecule
4. It then goes to the cell membrane to present itself to a CD4 cell (t-helper cell)

Question 16

What type of vaccine would follow the endogenous pathway?

Answer 16

live vaccines

Question 17

Where must the protein be located in the endogenous pathway?

Answer 17

in the cytoplasm

Question 18

What are the steps of the endogenous pathway?

Answer 18

1. Protein is tagged with ubiquitin - for processing by a proteosome
2. It then goes into the lumen
3. The peptides are moved in to the MHC I pathway and then is presented to the membrane and the CD8 cell

Question 19

What is a proteosome?

Answer 19

a hollow cylinder that unfolds the protein and chops it into peptides

Question 20

What is the difference between the antigens presented in the endogenous pathway and the exogenous pathway?

Answer 20

the antigens presented in the endogenous pathway must be in the cytoplasm, whereas they are on the outside in the exogenous pathway

Question 21

How does ISCOM work?

Answer 21

It is able to carry proteins into the cytosol so that the protein can be presented on MHC I to stimulate a CD8 t cell response

Question 22

What are the benefits of using immune stimulatory complexes to deliver an inactivated antigen?

Answer 22

killed vaccines or purified proteins and stimulate CD8 cells by using this otherwise they are taken up via phagocytosis

Question 23

How many different MHC I molecules can an individual have?

Answer 23

6 molecules

Question 24

How many different MHC II molecules can an individual have?

Answer 24

8-10 molecules

Question 25

What is the MHC heterozygote advantage?

Answer 25

animals with 6 different MHC molecules can bind and present a greater variety of antigen where as homozygous animals with only 3 do not have a large variety of antigen

Question 26

What is the role of MHC in tissue transplantation?

Answer 26

T cells recognize peptides in the MHC type, if they are not all the same they are considered a foreign MHC which can lead to rejection and death of cells