Deck 7: The Major Histocompatibility Complex and Antigen Presentation

Question 1

MHC molecules

A)are secreted by T cells and bind and neutralize antigen in the serum.
B)are membrane-bound molecules found exclusively on T cells.
C)bind repeating patterns found on pathogens.
D)are recognized by T cells.
E)are conserved between individuals.

Answer 1

D

Question 2

A mutation in which part of a viral protein might allow the virus to evade the adaptive immune response because of its MHC binding?

A)A TCR contact residue
B)A residue in the transmembrane domain of an envelope protein
C)A residue in the DNA-binding domain
D)An anchor residue
E)An amino acid on the surface of the virus

Answer 2

D

Question 3

MHC polymorphisms tend to cluster

A)in the peptide-binding groove.
B)in the transmembrane domain.
C)in the coreceptor contact residues.
D)in the framework region.
E)All of the answers are correct.

Answer 3

A

Question 4

Of the classical MHC genes, which, could you argue, are LEAST related to antigen presentation?

A)MHC I genes
B)MHC II genes
C)MHC III genes
D)Both MHC I and II genes
E)None of the answers are correct.

Question 5

Based on your knowledge of MHC I and II, predict which cell type would be MOST likely not to express detectable MHC I.

A)Dendritic cells
B)Macrophages
C)Erythrocytes
D)Intestinal epithelial cells
E)Basophils

Question 6

Which of the following are functions related to the expression of MHC molecules?

A)To display self-peptides to demonstrate cell health
B)To display foreign peptides
C)To display self-peptides to test developing T cells for autoreactivity
D)To display self-peptides to maintain self-tolerances
E)All of the answers are correct.

Question 7

Of the cells listed below, predict which is LEAST likely to be presenting antigens by MHC II during an immune response to an extracellular pathogen.

A)Dendritic cells
B)Macrophages
C)B cells
D)Intestinal epithelial cells
E)None of the answers are correct.

Question 8

MHC expression is constitutive; however, levels of MHC I and II can vary depending on conditions.Which of the following is NOT known to influence MHC expression levels?

A)CITA and CIIITA
B)Hepatitis B infection
C)IL-4 levels
D)Corticosteroids
E)All of the answers are factors that can influence MHC levels.

Question 9

How many different MHC classical class I proteins does each nucleated cell in a human heterozygous at the MHC locus express?

A)None.Only APC express class I.
B)One
C)Two
D)Three
E)Six

Question 10

Which of the following would be the MOST likely source of a peptide bound to an MHC class I molecule?

A)The Golgi apparatus
B)Outside the cell
C)The endosome/lysosome
D)The cytoplasm
E)The chloroplast

Question 11

One way a developing fetus is protected from attack by the maternal immune system is

A)expression of paternal MHC class I molecules.
B)expression of paternal MHC class II molecules.
C)expression of nonclassical class I molecules.
D)expression of nonclassical class II molecules.
E)expression of class III MHC molecules.

Question 12

Which of the following is NOT a mouse MHC gene?

A)IA
B)IE
C)DP
D)D
E)K

Question 13

Peptide-binding diversity is increased by

A)multiple MHC alleles in the population, only.
B)multiple homologous MHC genes in the genome, only.
C)both multiple MHC alleles in the population and multiple homologous MHC genes in the genome.
D)None of the answers are correct.

Question 14

Your chances of having the same MHC haplotype as your sibling are

A)1:1.
B)1:2.
C)1:4.
D)1:8.
E)1:16.

Question 15

The human MHC locus is one of the most polymorphic regions of the genome.What does this mean?

A)It has the most different genes.
B)There are many different alleles of these genes.
C)Sequence variability is low in this region.
D)There are many introns in this region.
E)This region is regulated by many different mechanisms.

Question 16

MHC diversity ultimately affects the

A)variety of peptides that bind to MHC.
B)variety of BCRs that are expressed on mature B cells.
C)rate of somatic hypermutation.
D)number of antigen-presenting cells.
E)transmembrane domain.

Question 17

Which of the following BEST represents the relationship of polypeptide units in MHC class II?

A) ? and ? chains from any gene can pair with each other
B)Only . ? and ? chains from the same gene can pair with each other
C)Only ? and ? chains of the same allele can pair with each other
D) ?
Chains can pair with other ? chains, but ? ? chains can only pair with chains.
E) ? and ? chains pair until the complex is exported to the cell surface and can bind ? 2-microglobulin

Question 18

Tasmanian devils are a largely inbred population with little diversity in the MHC.Which of the following would be a likely outcome of this?

A)They would compensate for low diversity in the MHC with high diversity in the TCR.
B)They would compensate for low diversity in the MHC with high diversity in the BCR.
C)They would rely only on innate immune responses.
D)They would be at higher risk of infection.
E)All of the answers are correct.

Question 19

Which of the following cell types would be LEAST likely to express MHC class II?

A)B cells
B)T cells
C)Dendritic cells
D)Thymic epithelial cells
E)Vascular endothelial cells

Question 20

Which of the following cell types would be MOST likely to express MHC class I?

A)B cells
B)T cells
C)Dendritic cells
D)Lung epithelial cells
E)All of the answers are correct.

Question 21

Which of the following is the BEST example of self-MHC restriction of T cells?

A)A T-cell clone is deleted when it binds too tightly to self-MHC.
B)A T-cell clone responds more vigorously to a self-peptide than a foreign peptide.
C)A T-cell clone recognizes foreign MHC.
D)A T-cell clone only recognizes foreign peptides when presented by self-MHC.
E)All of the answers are correct.

Question 22

Under which of the following conditions would T-cell activation be LEAST likely to occur?

A)Macrophages are incubated with antigen, then fixed with paraformaldehyde, then incubated with antigen-specific T cells.
B)Macrophages are fixed with paraformaldehyde, then incubated with antigen, then incubated with antigen-specific T cells.
C)Macrophages are fixed with paraformaldehyde, then incubated with digested antigen, then incubated with antigen-specific T cells.
D)Macrophages are incubated with digested antigen, then fixed with paraformaldehyde, then incubated with antigen-specific T cells.
E)Macrophages are incubated with antigen and then incubated with antigen-specific T cells.

Question 23

Place the class I processing pathway in the correct order:

A)Peptides exported from the ER by TAP > peptides are digested by the proteasome > peptides are loaded onto class I > class I is exported to the cell surface
B)Proteins are digested by the proteasome > peptides are imported into the ER by TAP > peptides are loaded onto MHC class I > class I is exported to the cell surface
C)MHC class I moves from the cell surface to the lysosome by endocytosis > class I bound peptides are replaced with antigenic peptides in the lysosome > class I returns to the cell surface
D)Proteins are degraded by TAP > peptides are imported into the lysosome by the proteasome > peptide-MHC class I complexes are exported to the cell surface
E)MHC class I is transported to the ER by TAP > proteins in the ER are degraded into peptides by the proteasome > peptides bind MHC class I in the ER, and the complex is exported to the cell surface

Question 24

In people infected with human cytomegalovirus, class I MHC and ? ₂-microglobulin are produced, but very little mature class I MHC is found at the cell surface.Inhibition of which of the following molecules by human cytomegalovirus may account for this phenomenon?

A)TCR
B)RAG
C)CLIP
D)TAP
E)Ii

Question 25

T-cell activation can be inhibited by treating antigen-presenting cells with chloroquine.What is chloroquine's mechanism of action?

A)It blocks protein synthesis.
B)It disrupts the Golgi apparatus.
C)It increases the pH of the lysosome.
D)It blocks TLR signaling.
E)All of the answers are correct.

Question 26

What is the role of the invariant chain (Ii)?

A)To prevent peptide binding to class II in the ER
B)To assist in folding class II ? and ? chains
C)To direct class II to the endocytic compartment
D)To serve as a substrate for proteases in the lysosome
E)All of the answers are correct.

Question 27

A mutation that renders the MHC class II molecule DM nonfunctional would likely lead to

A)cells with no class II MHC.
B)cells with no DO.
C)cells with class II MHC only bound with CLIP.
D)cells with class II MHC bound with a variety of self-antigens.
E)a deficiency in CD8⁺ T cells.

Question 28

Which of the following is an example of cross presentation?

A)An endogenous peptide being presented on MHC class I
B)An exogenous peptide being presented on MHC class I
C)An endogenous peptide being presented on MHC class II
D)An exogenous peptide being presented on MHC class II
E)A B-cell antigen being presented to a T cell

Question 29

Of the antigen receptors listed here - T-cell receptor, B-cell receptor, MHC I, and MHC II - which would you describe as "promiscuous" in their ligand-binding activity?

Question 30

Examine Figure 7-4.(in the text) Can you summarize, in two sentences maximum, what this figure demonstrates about MHC I-peptide antigen interactions?

Question 31

You might have noticed that two people may respond to the same bacterial pathogen differently.Although "Person A" might only suffer a minor disease, "Person B" may take longer to clear the same pathogen.Argue how this discrepancy can be explained, at least in part, by the determinant selection model.

Question 32

B-cell receptor and T-cell receptor diversity is generated through genomic rearrangement and gene editing mechanisms.Compare those mechanisms with mechanisms used to generate MHC diversity in an individual.How are the mechanisms the same, and how are they different?

Question 33

Name the primary factor contributing to the observation that human genes found within the MHC locus are inherited as a set, which is described by geneticists as a linkage disequilibrium pattern of inheritance.

Question 34

You have two brothers and a sister, and your parents have different haplotypes.Are you more likely to be histocompatible with a sibling within your family or your parents?

Question 35

Compare and contrast the holes-in-the-repertoire model and the determinant-selection model of immune responsiveness.

Question 36

Name an advantage of presenting viral antigens by both the endogenous and exogenous pathways.

Question 37

Suppose an individual is deficient in TAP (transporter associated with antigen processing).Is the deficiency MORE likely to produce symptoms of immune deficiency or autoimmunity in the person?

Question 38

In your own words, explain how the immune system can activate CD8⁺ T-cells to eliminate intracellular pathogens (i.e., viruses) unless a dendritic cell happens to become infected.

Question 39

Nonprotein antigens are not recognized by T cells.Is this statement true or false? Justify your answer.