MHC Antigen Processing (Exam 2) Flashcards
Term for having more than one allele for a gene.
polymorphism
_______ are the most polymorphic genes known with some having greater than 250 different alleles.
MHC genes
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.
polygenism
Term for all genes on MHC molecules being equally expressed.
co-dominance
Term for when individuals express same alleles for a gene.
syngeneic
Term for when individuals express at least one different allele.
allogeneic
What is an allele?
variation of a gene at the same place on a chromosome
List the symbols used for mouse MHC nomenclature for Class I genes, Class II genes, and alleles.
Class I: K, D, L
Class II: A, E
Alleles: lowercase letters (a, b, c)
What is the shorthand for Class I MHC molecule nomenclature for mice? Class II?
Class I: H-2
Class II: I-A
In the example H-2K^d, what do each symbol represent? Is it mouse or human MHC molecule?
Mouse
H-2: Class I MHC molecule
K: Class I gene
d: allele
List the symbols used for human MHC nomenclature for Class I genes, Class II genes, and alleles.
Class I: A, B, C
Class II: DP, DQ, DR
alleles: numbers (1,2,3)
What shorthand is used to identify a human MHC molecule?
HLA (human leukocyte antigen)
In the MHC molecule example, HLA-DR4, what do each symbol represent? Is it from a human or mouse?
human
HLA: human MHC molecule
DR: Class II gene
4: allele
In MHC restriction, T cells from an individual can only respond to antigen if it recognizes what two things?
- peptide
- MHC molecule
Term for a set of MHC alleles for a given individual.
MHC haplotype
Term for when T cells must recognize both a peptide and its bound MHC molecule to create a response.
MHC restriction
In terms of Class I MHC structure, it is made up of a _______ and ______.
B2-microglobulin
alpha chain
Class II MHC molecules are made up of _______ and ______.
half alpha + half beta chain
To be considered fully assembled, a Class I MHC molecule needs to have these 3 things:
- alpha chain
- B2-microglobulin
- bound peptide
Class I MHC are expressed on ________ cells while Class II MHC are expressed on ________ cells.
nucleated
antigen-presenting
Peptides that bind to Class I MHC come from (inside/outside) the cell while for Class II MHC come from (inside/outside) the cell.
inside
outside
Which CD on T cells do Class I and Class II MHC molecules bind?
Class I: CD8
Class II: CD4
Where does peptide bind on MHC molecules?
peptide-binding cleft
What structures of peptide side chains allow for tight and specific binding to peptide-binding cleft on MHC molecules?
anchor residues
T cells recognize antigen only as _____.
short linear peptides
(T/F) T cells only recognize antigens when they are presented to them on MHC as peptides.
True
Term for a microbial product that enhances antigen presentation, as used in vaccines to improve their effectiveness.
adjuvant
What is meant by a “professional antigen-presenting cell”?
express class II MHC molecules and present antigen to CD4 T cells
Regarding the process of antigen capture and presentation, _________ capture antigen and activated ________ travel through lymphatics to present antigen to _______.
tissue-resident dendritic cells
dendritic cells
T cells
Cross-presentation is a specific antigen-processing pathway in (class I/class II) MHC molecules since you need to activate (CD4/CD8) cells.
Class I
CD8
Explain cross-presentation.
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
Fill in the appropriate blanks for Class I MHC antigen-processing pathway.
- Antigen enters cell as ______.
- A _______ tag targets antigen for degradation into peptides.
- Peptides are transported into ER via _____.
- Peptides bind to Class I MHC.
- MHC molecules are transported out via _______ and onto cell surface.
cytosolic protein
ubiquitin
TAP (transport associated protein)
golgi vesicles
Fill in the appropriate blanks for Class II MHC antigen-processing pathway.
- Antigens enters cell as ________.
- ______ breaks antigen –> peptides.
- In ER, _______ is added to class II molecules.
endocytic vesicles
lysosome
invariant chain
What is the purpose of the invariant chain?
prevent Class II MHC from binding to other peptides in ER and guides it to vesicles with appropriate peptides
Once outside of the ER, the invariant chain on Class II MHC is broken down except _______.
CLIP
What molecule removes CLIP from Class II MHC so a peptide can bind?
HLA-DM
Term for membrane-bound vesicles in cytosol that carry antigen in the Class II MHC antigen-presenting pathway.
endosome
(T/F) CLIP is easily degraded from Class II MHC molecules.
False
_______ is a protein complex that degrades proteins into peptides for the Class I MHC pathway.
proteasome
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.
immunodominant epitopes
