MHC Antigen Processing (Exam 2)

Question 1

Term for having more than one allele for a gene.

Answer 1

polymorphism

Question 2

_______ are the most polymorphic genes known with some having greater than 250 different alleles.

Answer 2

MHC genes

Question 3

Term for MHC having different class I and II genes so each individual has a different set of MHC molecule with unique peptide-binding specificity.

Answer 3

polygenism

Question 4

Term for all genes on MHC molecules being equally expressed.

Answer 4

co-dominance

Question 5

Term for when individuals express same alleles for a gene.

Answer 5

syngeneic

Question 6

Term for when individuals express at least one different allele.

Answer 6

allogeneic

Question 7

What is an allele?

Answer 7

variation of a gene at the same place on a chromosome

Question 8

List the symbols used for mouse MHC nomenclature for Class I genes, Class II genes, and alleles.

Answer 8

Class I: K, D, L
Class II: A, E
Alleles: lowercase letters (a, b, c)

Question 9

What is the shorthand for Class I MHC molecule nomenclature for mice? Class II?

Answer 9

Class I: H-2
Class II: I-A

Question 10

In the example H-2K^d, what do each symbol represent? Is it mouse or human MHC molecule?

Answer 10

Mouse
H-2: Class I MHC molecule
K: Class I gene
d: allele

Question 11

List the symbols used for human MHC nomenclature for Class I genes, Class II genes, and alleles.

Answer 11

Class I: A, B, C
Class II: DP, DQ, DR
alleles: numbers (1,2,3)

Question 12

What shorthand is used to identify a human MHC molecule?

Answer 12

HLA (human leukocyte antigen)

Question 13

In the MHC molecule example, HLA-DR4, what do each symbol represent? Is it from a human or mouse?

Answer 13

human
HLA: human MHC molecule
DR: Class II gene
4: allele

Question 14

In MHC restriction, T cells from an individual can only respond to antigen if it recognizes what two things?

Answer 14

1. peptide
2. MHC molecule

Question 15

Term for a set of MHC alleles for a given individual.

Answer 15

MHC haplotype

Question 16

Term for when T cells must recognize both a peptide and its bound MHC molecule to create a response.

Answer 16

MHC restriction

Question 17

In terms of Class I MHC structure, it is made up of a _______ and ______.

Answer 17

B2-microglobulin
alpha chain

Question 18

Class II MHC molecules are made up of _______ and ______.

Answer 18

half alpha + half beta chain

Question 19

To be considered fully assembled, a Class I MHC molecule needs to have these 3 things:

Answer 19

1. alpha chain
2. B2-microglobulin
3. bound peptide

Question 20

Class I MHC are expressed on ________ cells while Class II MHC are expressed on ________ cells.

Answer 20

nucleated
antigen-presenting

Question 21

Peptides that bind to Class I MHC come from (inside/outside) the cell while for Class II MHC come from (inside/outside) the cell.

Answer 21

inside
outside

Question 22

Which CD on T cells do Class I and Class II MHC molecules bind?

Answer 22

Class I: CD8
Class II: CD4

Question 23

Where does peptide bind on MHC molecules?

Answer 23

peptide-binding cleft

Question 24

What structures of peptide side chains allow for tight and specific binding to peptide-binding cleft on MHC molecules?

Answer 24

anchor residues

Question 25

T cells recognize antigen only as _____.

Answer 25

short linear peptides

Question 26

(T/F) T cells only recognize antigens when they are presented to them on MHC as peptides.

Answer 26

True

Question 27

Term for a microbial product that enhances antigen presentation, as used in vaccines to improve their effectiveness.

Answer 27

adjuvant

Question 28

What is meant by a “professional antigen-presenting cell”?

Answer 28

express class II MHC molecules and present antigen to CD4 T cells

Question 29

Regarding the process of antigen capture and presentation, _________ capture antigen and activated ________ travel through lymphatics to present antigen to _______.

Answer 29

tissue-resident dendritic cells
dendritic cells
T cells

Question 30

Cross-presentation is a specific antigen-processing pathway in (class I/class II) MHC molecules since you need to activate (CD4/CD8) cells.

Answer 30

Class I
CD8

Question 31

Explain cross-presentation.

Answer 31

dendritic cells sample antigen that is degraded and released in the cytosol so Class I MHC can bind to it and go to cell surface to activate CD8 cells

Question 32

Fill in the appropriate blanks for Class I MHC antigen-processing pathway.

1. Antigen enters cell as ______.
2. A _______ tag targets antigen for degradation into peptides.
3. Peptides are transported into ER via _____.
4. Peptides bind to Class I MHC.
5. MHC molecules are transported out via _______ and onto cell surface.

Answer 32

cytosolic protein
ubiquitin
TAP (transport associated protein)
golgi vesicles

Question 33

Fill in the appropriate blanks for Class II MHC antigen-processing pathway.

1. Antigens enters cell as ________.
2. ______ breaks antigen –> peptides.
3. In ER, _______ is added to class II molecules.

Answer 33

endocytic vesicles
lysosome
invariant chain

Question 34

What is the purpose of the invariant chain?

Answer 34

prevent Class II MHC from binding to other peptides in ER and guides it to vesicles with appropriate peptides

Question 35

Once outside of the ER, the invariant chain on Class II MHC is broken down except _______.

Answer 35

CLIP

Question 36

What molecule removes CLIP from Class II MHC so a peptide can bind?

Answer 36

HLA-DM

Question 37

Term for membrane-bound vesicles in cytosol that carry antigen in the Class II MHC antigen-presenting pathway.

Answer 37

endosome

Question 38

(T/F) CLIP is easily degraded from Class II MHC molecules.

Answer 38

False

Question 39

_______ is a protein complex that degrades proteins into peptides for the Class I MHC pathway.

Answer 39

proteasome

Question 40

Term for when a specific peptide of a degraded antigen has a better affinity for MHC molecule which causes most T cells to respond to that one epitope and undergo clonal expansion.

Answer 40

immunodominant epitopes