Exam 2: Dr. Pinchuk Antigen Processing and Presentation

Question 1

In what form does TCR antigen recognition occur?

Answer 1

Only in the form of peptide bound to an MHC molecule on the surface of APC

Question 2

What are the 2 things that occur in TCR antigen recognition?

Answer 2

Antigen processing and antigen presentation

Question 3

What is antigen processing?

Answer 3

Pathogen-derived proteins must be degrade into peptides by APCs

Question 4

What is antigen presentation?

Answer 4

When peptides are assembled into peptide:MHC complexes for display on the APC surfaces

Question 5

What are the steps to antigen processing and presentation?

Answer 5

Protein antigen is in the cell
Antigen processing occurs by breakdown of protein
Presentation of peptide by MHC molecule

Question 6

What do the 2 classes of MHC present antigens to?

Answer 6

CD8 and CD4 T cells

Question 7

What co-receptor is MHC class I associated with?

Answer 7

CD8

Question 8

What co-receptor is MHC class II associated with?

Answer 8

CD4

Question 9

What do MHC molecules bind?

Answer 9

A variety of peptides in different intracellular compartments

Question 10

What does TCR specifically recognize?

Answer 10

Both peptide (foreign) and MHC (self) molecules

Question 11

What are dendritic cells?

Answer 11

Universal antigen presenting cells

The best presenting cells

Question 12

What are macrophages when they are in blood circulation?

Answer 12

Monocytes

Question 13

Where are dendritic cells located in the lymph node?

Answer 13

T cell areas

Question 14

How do dendritic cells do antigen uptake?

Answer 14

Macropinocytosis and phagocytosis by tissue dendritic cells

Viral infection

Question 15

What is MHC expression like in dendritic cells?

Answer 15

Low on tissue DCs

High on DCs in lymphoid tissues

Question 16

What is the co-stimulatory delivery of DCs?

Answer 16

Constitutive by mature, nonphagocytic lymphoid dendritic cells

Question 17

What is the antigen presented to DCs?

Answer 17

Peptides
Viral antigens
Allergens

Question 18

What is the location of DCs?

Answer 18

Ubiquitous throughout the body

Question 19

What is the process of antigen uptake in macrophages?

Answer 19

Phagocytosis

Question 20

What is MHC expression like for macrophages?

Answer 20

Inducible by bacteria and cytokines

Question 21

What is the co-stimulatory delivery for macrophages like?

Answer 21

Inducible

Question 22

What is the antigen presented to macrophages?

Answer 22

Articulate antigens

Intracellular and extracellular pathogens

Question 23

What is the location of macrophages?

Answer 23

Lymphoid tissue
Connective tissue
Body cavities

Question 24

What is the location of B cells in the lymph node?

Answer 24

Follicle

Question 25

What is antigen uptake like for B cells?

Answer 25

Antigen-specific receptor

Question 26

What is MHC expression like for B cells?

Answer 26

Constitutive | Increases on activation

Question 27

What is the co-stimulatory delivery like for B cells?

Answer 27

Inducible

Question 28

What antigen is presented to B cells?

Answer 28

Soluble antigens Toxins Viruses

Question 29

What is the location of B cells?

Answer 29

Lymphoid tissue | Peripheral blood

Question 30

What makes B cell different than other APCs?

Answer 30

It belongs to the adaptive immune system

Question 31

What cells do not have MHC class I?

Answer 31

RBCs

Question 32

What do immature DCs do?

Answer 32

Uptake and process antigen

Question 33

What do mature DCs do?

Answer 33

Present antigen

Question 34

Where are immature DCs located?

Answer 34

Peripheral tissues

Question 35

Where are DCs that are processing antigen located?

Answer 35

Lymphatic location

Question 36

Where are mature DCs located?

Answer 36

Lymphoid tissues

Question 37

What are the 2 models of DC maturation?

Answer 37

Classical model | Revised model

Question 38

What happens in the classical model?

Answer 38

Pathogen-induced migration

Question 39

What happens in the revised model?

Answer 39

Steady state migration | Pathogen induced migration

Question 40

What is pathogen-induced migration?

Answer 40

Migration of immature DC from the periphery to the T cell areas of the lymph nodes only in response to microbial stimulation (infection)

Question 41

What is steady state migration?

Answer 41

Occurs constitutively in the apparent absence of microbial stimulation The mechanism by which DCs can sample and engulf self-proteins and "food antigens" to naive T cells to establish and maintain peripheral tolerance to such antigens

Question 42

What is the rule of antigen presentation for direct presentation with MHC class I?

Answer 42

Peptides generated in the cytosol are transported into the endoplasmic reticulum, where they bind MHC class I and presented to CD8 T cells

Question 43

What is the rule of antigen presentation for direct presentation with MHC class II?

Answer 43

Peptides generated in acidified intracellular vesicles presented by MHC class II and presented to CD4 T cells

Question 44

What is the exception to antigen presentation for cross-presentation?

Answer 44

Allows extracellular antigens to be processed and displayed within MHC class I to CD8 T cells

Question 45

Why can cross-presentation be done?

Answer 45

Because it enhances MHC

Question 46

What is the second exception to antigen presentation?

Answer 46

Peptides from pathogens that can flourish in the cytosol can cross over

Question 47

What are peptides processed through?

Answer 47

Proteosomes

Question 48

What kind of antigen presentation is receptor-mediated endocytosis of bacteria?

Answer 48

Direct presentation

Question 49

What kind of antigen presentation is macropinocytosis of bacteria or viruses?

Answer 49

Direct presentation

Question 50

What kind of antigen presentation is viral infection?

Answer 50

Cross-presentation

Question 51

What kind of antigen presentation do exogenous viral antigens use?

Answer 51

Cross-presentation

Question 52

What kind of antigen presentation is transfer of viral antigens from infected DC to resident DC?

Answer 52

Cross-presentation

Question 53

Look at direct and cross-presentation picture

Answer 53

Look at direct and cross-presentation picture

Question 54

What can cross presentation explain the direct presentation cannot?

Answer 54

How CD8 T cells responses are primed to infectious organisms that do not infect APCs How DCs prime cytotoxic T cells against pathogens that are restricted to the endocytic pathway and never reach the cytosol Pathogen infected DCs are often functionally compromised, but they present antigens efficiently

Question 55

What is dendritic cell nibbling?

Answer 55

Cross-presentation | DC meets the infected cell and chops the head off of the infected cell (extracellular uptake)

Question 56

What is autophagy?

Answer 56

``` Presentation of cellular antigens by MHC class II Self-eating ```

Question 57

In the research that discovered autophagy, why were yeast systems used?

Answer 57

They multiply quickly and generate multiple clones

Question 58

What are the principal manifestations of immunological autophagy?

Answer 58

Direct pathogen elimination Regulation and effector functions of PRRs Regulation of inflammasome activation and alarming secretion Cytoplasmic antigen processing for MHC II presentation and T cell homeostasis

Question 59

What cells express MHC class I?

Answer 59

``` T cells B cells Macrophages DCs Neutrophils ```

Question 60

What cells express MHC class II?

Answer 60

B cells Macrophages DCs Thymic epithelium

Question 61

What is degenerate binding specificity?

Answer 61

MHC molecules have peptide-binding sites that are capable of binding peptides of many different amino acid sequences

Question 62

What is the peptide-binding groove?

Answer 62

The peptide-binding site on the surface of the MHC molecule with which a single peptide is held tightly by non-covalent bonds