CHP 6 - T cell antigen recognition

Question 1

When do effector cells generate?

Answer 1

During clonal selection

Question 2

Where does MHC diversity generate from?

Answer 2

Due to MHC gene families and genetic polymorphism, it is not due to recombination like T cell receptor and B cell.

Question 3

What are the two types of functions of the genes that are activated from the T cell receptor MHC peptide complex?

Answer 3

1) for T cell to undergo proper division and differentiation
2) Genes required to carry out the effector functions of the activated T cell

Question 4

Cytotoxic cells are activated ______ T cell that target cells that are infected with _____________ pathogens

Answer 4

CD8; intracellular

Question 5

Helper T cells are activated ________ T cells that activate cells that combat ____________ pathogens.

Answer 5

CD4; extracellular

Question 6

What does the T cell receptor lack? – must need other cell surface molecules to do this

Answer 6

lacks the ability to initiate intracellular signaling events on its own due to lack of cytoplasmic domain

Question 7

CD28 is an essential costimulatory signal for naive T cell activation by resulting in a (+/-) signal

Answer 7

Positive

Question 8

CTLA4 binds to __________ on a APC and down regulates T cell activation

Answer 8

CD80/86

Question 9

CD28 and CTLA4 compete for _______ and ________ binding

Answer 9

Cd80 and Cd86

Question 10

Binding of CTLA4 and CD80/CD86 results in which type of signaling?

Answer 10

Negative

Question 11

The alpha chain of MHC I anchors MHC to?

Answer 11

Plasma membrane

Question 12

The peptide binding groove binds peptides that are ___ to ____ amino acids long

Answer 12

8 to 10

Question 13

What quality do MHC receptors have to allow a single MHC molecule to bind to a variety of peptides?

Answer 13

Promiscuous binding specificity

Question 14

Somatic recombination of T cell receptor chains can result in?

Answer 14

Productive rearrangement or unproductive rearrangement

Question 15

CD8 molecule makes contact with structural domain of the ___-subunit of MHC class I

Answer 15

Alpha

Question 16

When the alpha chain of MHC I enters the ER, what molecule interacts with MHC to chaperone and assist in the addition of B2-microglobulin?

Answer 16

Calnexin

Question 17

What is the function of tapsin?

Answer 17

1) allows efficient peptide loading on MHC I class
2) promotes association of peptide that can bind tightly to MHC class I

Question 18

What is the function of calreticulin in regard to MHC class I loading?

Answer 18

promotes proper assembly of MHC class I molecules with the tightly bound peptide

Question 19

Which molecule is responsible for keeping MHC class I molecule in the ER until they have become properly folded?

Answer 19

Calnexin

Question 20

Which molecule is responsible for cleaving intracellular proteins into small peptides of varying lengths?

Answer 20

Proteasome

Question 21

Cytokines secreted during an inflammatory response can produce?

Answer 21

immunoproteasome

Question 22

Which molecule is responsible for transportation of peptides into the ER membrane?

Answer 22

Transporter associated with antigen processing (TAP)

Question 23

What is peptide trimming? Which molecule is responsible for this?

Answer 23

The removal of amino acids from a peptide – protease ERAP trims the N-terminal

Endoplasmic reticulum aminopeptidase

Question 24

Which molecule is responsible for ensuring the tight bounding of peptides in the peptide binding groove?

Answer 24

Tapasin

Question 25

What are the five major steps for peptide loading onto a MHC molecule?

Answer 25

1) Formation of the peptide loading complex (MHC) 2) Digestion of proteins by proteasome 3) Peptide transportation to the ER 4) Peptide trimming to ensure tight binding between MHC and antigen 5) Transportation of MHC-peptide complex to the plasma membrane for presentation

Question 26

What is the one major difference between MHC I class peptide loading vs MHC II class peptide loading?

Answer 26

MHC class I peptide loading occurs in the ER MHC class II peptide loading occurs outside the ER in a vesicle (secretory pathway)

Question 27

MHC class II are not capable of loading peptide until they are part of a vesicle capable of fusing with a ________________.

Answer 27

Phagolysosome

Question 28

What are the four steps of MHC II loading?

Answer 28

1) MHC class II molecule assembly in the ER 2) Clip production 3) Phagocytosis and fusion with the MHC compartment 4) Peptide loading

Question 29

Which protein is responsible for assembling the MHC II molecule in the ER and blocks the peptide binding groove?

Answer 29

Invariant chain

Question 30

Which protease cleaves the invariant chain and leaves CLIP bound on the peptide-binding groove?

Answer 30

Cathepsin S

Question 31

Which antigen promotes the exchange of CLIP for lysosomal peptides?

Answer 31

HLA-DM

Question 32

What is MHC cross presentation?

Answer 32

One cell having the ability to stimulate both CD4 and CD8 T cells at any time.

Question 33

Which type of cell is known for being an expert at MHC cross presentation?

Answer 33

Dendritic cells