Lecture 3 - Antigen Processing and Presentation (Stiner)

Question 1

Which cells are professional antigen presenting cells (APCs?

Answer 1

Dendritic cells
Macrophages
B cells

Question 2

Which MHC do most nucleated cells in the body use to present antigen?

Answer 2

MHC 1

This is important in cancer b/c cytotoxic T-cells can see antigens presented in the context of MHC 1

Question 3

What are the two pathways of Antigen presentation?

Answer 3

1. EXOgenous

2. ENDOgenous

Question 4

Which pathway involves MHC ii and T-helper cells?

Answer 4

EXOgenous

Question 5

Which pathway involves MHC I and cytotoxic T- cells?

Answer 5

ENDOgenous

Question 6

What are the two pathways for antigen PROCESSING?

Answer 6

1. Cytoplasmic Pathway (for endogenous antigens, recognized by CD8+ T cells)
2. Endocytic Pathway (for exogenous antigens, recognized by CD4+ T cells)

Question 7

Which antigen processing pathway uses proteasomes to break down cytoplasmic proteins?

Answer 7

Cytoplasmic pathway (for endogenous antigens recognized by CD8+ T cells)

Question 8

Which antigen processing pathway uses lysosomes to break down endocytic proteins?

Answer 8

Endocytic pathway (for exogenous antigens recognized by CD4+ T cells)

Question 9

***How does an MHC molecule make it from the ER (site of synthesis) to the cell membrane?

Answer 9

1. MHC is associated with an INVARIANT CHAIN that keeps it from binding to anything.
2. It is carried in an endosome.
3. Invariant chain is digested, and now CLIP hangs out in the binding site of MHC.
4. HLA-DM reMoves CLIP from MHC binding site, and MHC moves to cell surface.
   * **HLA-DO blOcks HLA-DM & therefore keeps CLIP in binding site & MHC off cell surface.

Question 10

How are MHC I and MHC II different?

Answer 10

MHC I 
   -small
    -made of one protein
    -antigen binds only to the END of MHC I
MHC 2
    -wider
    -made of two proteins
    -antigen binds ALONG LENGTH of MHC II

Question 11

What can an MHC haplotype influence? (3)

Answer 11

1. response to pathogens
2. susceptibility to certain diseases
3. transplant success

Question 12

What is an MHC haplotype?

Answer 12

The set of MHC alleles on an individual chromosome

Question 13

Do MHC molecules discriminate from self and non-self?

Answer 13

No, they have a broad specificity for peptides.

Question 14

What is needed for a CD8+ T-cell to become activated? Two signals.

Answer 14

1. Primary stimulus
   
   • T-cell receptor bind to MHC I on APC
2. Secondary stimulus
   
   • CD28 on T cell binds to B7 on APC

Question 15

Where is B7 located?

Answer 15

on an APC presenting to a CD8+ T cells

Question 16

Where is CD28 located?

Answer 16

on a T-cell that is getting info from an APC. CD28 connected to APC’s B7

Question 17

What are the adhesion molecules involved in the CD8+ activation?

Answer 17

ICAM-1 on APC binds to LFA-1 on T cell

Question 18

Where is ICAM-1 found?

Answer 18

on APC presenting to CD8+ cell.
Adhesion molecule.
ICAM-1 binds to LFA-1

Question 19

Where is LFA-1 found?

Answer 19

on CD8+ T cell getting info from an APC cell.
Adhesion molecule.
LFA-1 binds to ICAM-1

Question 20

What is the order of events during CD8+ activation?

Answer 20

1. Adhesion (LFA-1 binds to ICAM-1)
2. Ag-specific activation (TCR binds to MGC I)
3. Costimulation (CD28 binds to B7)

Question 21

What type of proteins to CD8+ T cells recognize?

Answer 21

cytosolic proteins

Question 22

What type of proteins to CD4+ T cells recognize?

Answer 22

extracellular and intravesicular proteins

Question 23

What are the 3 components of TCR?

Answer 23

1. TCR
2. Zeta chains
3. CD3
   (CD3 and zeta chains are required for signaling.)

Question 24

What costimulatory receptor binds to B7 on APCs during T-cell activation?

Answer 24

CD28 on T cell surface

Question 25

What receptor replaces CD28 on T cell surface once in the infection has been taken care of? We need to downregulate T cell activity.

Answer 25

CTLA-4 is now on the surface of the T cell. It also binds with B7 on APC

Question 26

***What is the primary cytokine that T cells produce?

Answer 26

IL-2

Question 27

What does the T-cell produce when it is activated?

Answer 27

IL-2

Question 28

How does IL-2 amplify the T-cell response?

Answer 28

Adds an alpha segment to IL-2R, and therefore increases its affinity by 1000-fold

Question 29

What does IL-2 do, and why is it so potent?

Answer 29

1. T cell clonal expansion, differentiation into effector and memory cells 2. regulatory T cell development, survival, and function 3. NK cell proliferation, increased cytotoxic activity

Question 30

What is the costimulatory signal that B cells need from T cells to be activated?

Answer 30

CD40 (on B cell) binds to CD40L (on T-cell)

Question 31

Where is CD40?

Answer 31

B cell

Question 32

Where is CD40L?

Answer 32

T cell

Question 33

Which interleukin drives the development of TH1 cells?

Answer 33

IL-12

Question 34

What does IL-12 do?

Answer 34

drives development of TH1 cells

Question 35

What does IL-4 do?

Answer 35

Drives the development of TH2 cells | Potent inhibitor of TH1 response.

Question 36

What interleukin drives the development of TH2 cells?

Answer 36

IL-4

Question 37

What do TH1 cells help with?

Answer 37

cell-mediated immune responses 1. activate macrophages 2. complement antibodies and produce antibodies 3. activate neutrophils

Question 38

What to TH2 cells help with?

Answer 38

humoral immun responses (antibody)

Question 39

Which TH cell makes IFN-gamma?

Answer 39

TH1

Question 40

What cytokine does TH1 make?

Answer 40

IFN-gamma

Question 41

What does TH2 make?

Answer 41

IL-4

Question 42

What TH cell makes IL-4?

Answer 42

TH2