Immunology 6

Question 1

MHC class 1 is expressed in ..?

Answer 1

All nucleated cells

Question 2

MHC class2 is expressed in …?

Answer 2

professional APCs

Question 3

What domain of MHC class 2 binds CD4?

Answer 3

beta domain

Question 4

What domain of MHC class 1 binds CD8?

Answer 4

alpha domain

Question 5

TCR binds both the antigen and MHC molecule. True or False?

Answer 5

True

Question 6

Which of MHC Class-1 and Class-2 has a relatively closed groove so the binding occurs in pockets at the ends of the groove?

Answer 6

Class-1

Question 7

Describe the MHC class-2 antigen binding groove.

Answer 7

The groove is much more open so can accommodate bigger peptides and bind all along the length of the binding site.

Question 8

Where are peptides for MHC class-2 derived from?

Answer 8

Extracellular peptides.
(MHC-2 Synthesised in cell, translocate to ER, vesicles bud off and bind with peptides in antigen-processing compartment)

Question 9

Where are peptides for MHC class-1 derived from?

Answer 9

Intracellular peptides.

Often from when a cell is infected with a virus.

Question 10

Where are viral antigen broken down for presentation on MHC class-1?

Answer 10

proteasome
(peptide then binds to class 1 molecule in golgi and transported to surface.)

Question 11

What does interferon-gamma turn the proteasome into?

Answer 11

The immunoproteosome.

This contains additional subunits.

Question 12

What additional subunits does immunoproteosome contain that proteasome doesn’t?

Answer 12

LMP2, LMP7, MECL1

These change specificity of cleavage.

Question 13

What is the difference in function between immunoproteosome and proteasome?

Answer 13

There is an increased cleavage after hydrophobic residues so there are more peptides with C terminal hydrophobic residues which favours binding to MHC class 1.

Question 14

What is TAP?

Answer 14

Transporter for antigen processing. Transport degraded peptides from proteasome to endoplasmic reticulum

Question 15

What does Calnexin do?

Answer 15

Stabilises MHC class 1 heavy chain until beta-globulin binds and releases calnexin.

Question 16

In the endoplasmic reticulum what is the function of the chaperone proteins that interact with the MHC class 1?

Answer 16

Interact with MHC class I to hold it in open configuration so peptides can bind. They then dissociate.

Question 17

When a MHC class-1 molecule is loaded with a peptide that has too long an N-terminus what cleaves the peptide?

Answer 17

ERAP - an aminopeptidase

Question 18

What cleaves the invariant chain from the MHC class-2?

Answer 18

cathepsin S cleaves invariant chain forming CLIP (class-2 associated invariant peptide)

Question 19

What is the molecule that facilitates the release of CLIP called?

Answer 19

HLA-DM

Question 20

Is the Li-MHC 2 transported to the antigen processing compartment intact?

Answer 20

Yes

Question 21

What is the rare event cross-presentation?

Answer 21

When macrophages ingest an infected cell and degrade it. Peptides of the infected cells enter the endoplasmic reticulum and form MHC I complexes and are presented on the outside

Question 22

What is the major histomcompatibility complex?

Answer 22

A cluster of genes associated with antigen processing and presenting. This codes for the MHC molecules

Question 23

What is the histomcompatibility complex called in humans?

Answer 23

HLA (human leukocyte antigen)

Question 24

What is the histomcompatibility complex called in mice?

Answer 24

H2 complex

Question 25

Each MHC will have more than one major locus. True or False?

Answer 25

True In the example given there were 3, in fact there are more than this. As you have two chromosomes complexity is increased.

Question 26

Why is your complement of MHC unique to you?

Answer 26

These gene regions are highly polymorphic

Question 27

Why is it important to type donor tissue in transplant?

Answer 27

Otherwise cytotoxic T cells will recognise MHC class I on transplanted organ as foreign and will amount an immune respond against it.

Question 28

Why are differences in our alleles retained in the population?

Answer 28

Heterozygosity is an advantage. Certain alleles are associated with resistance to specific diseases. If we had the same sets a pathogen could and knock out a species.

Question 29

New MHC alleles are generated by ...?

Answer 29

Interalleic conversion between the same or different genes.

Question 30

B27 gives you a WHAT fold risk of developing Ankylosing spondylitis?

Answer 30

90

Question 31

which part of the TCR binds the peptide?

Answer 31

CDR3

Question 32

which part of the TCR binds the MHC?

Answer 32

CDR1 and CDR2