Exam 2: Dr. Pinchuk Antigen Processing and Presentation Flashcards

1
Q

In what form does TCR antigen recognition occur?

A

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

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2
Q

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

A

Antigen processing and antigen presentation

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3
Q

What is antigen processing?

A

Pathogen-derived proteins must be degrade into peptides by APCs

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4
Q

What is antigen presentation?

A

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

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5
Q

What are the steps to antigen processing and presentation?

A

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

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6
Q

What do the 2 classes of MHC present antigens to?

A

CD8 and CD4 T cells

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7
Q

What co-receptor is MHC class I associated with?

A

CD8

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8
Q

What co-receptor is MHC class II associated with?

A

CD4

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9
Q

What do MHC molecules bind?

A

A variety of peptides in different intracellular compartments

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10
Q

What does TCR specifically recognize?

A

Both peptide (foreign) and MHC (self) molecules

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11
Q

What are dendritic cells?

A

Universal antigen presenting cells

The best presenting cells

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12
Q

What are macrophages when they are in blood circulation?

A

Monocytes

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13
Q

Where are dendritic cells located in the lymph node?

A

T cell areas

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14
Q

How do dendritic cells do antigen uptake?

A

Macropinocytosis and phagocytosis by tissue dendritic cells

Viral infection

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15
Q

What is MHC expression like in dendritic cells?

A

Low on tissue DCs

High on DCs in lymphoid tissues

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16
Q

What is the co-stimulatory delivery of DCs?

A

Constitutive by mature, nonphagocytic lymphoid dendritic cells

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17
Q

What is the antigen presented to DCs?

A

Peptides
Viral antigens
Allergens

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18
Q

What is the location of DCs?

A

Ubiquitous throughout the body

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19
Q

What is the process of antigen uptake in macrophages?

A

Phagocytosis

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20
Q

What is MHC expression like for macrophages?

A

Inducible by bacteria and cytokines

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21
Q

What is the co-stimulatory delivery for macrophages like?

A

Inducible

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22
Q

What is the antigen presented to macrophages?

A

Articulate antigens

Intracellular and extracellular pathogens

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23
Q

What is the location of macrophages?

A

Lymphoid tissue
Connective tissue
Body cavities

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24
Q

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

A

Follicle

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25
Q

What is antigen uptake like for B cells?

A

Antigen-specific receptor

26
Q

What is MHC expression like for B cells?

A

Constitutive

Increases on activation

27
Q

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

A

Inducible

28
Q

What antigen is presented to B cells?

A

Soluble antigens
Toxins
Viruses

29
Q

What is the location of B cells?

A

Lymphoid tissue

Peripheral blood

30
Q

What makes B cell different than other APCs?

A

It belongs to the adaptive immune system

31
Q

What cells do not have MHC class I?

A

RBCs

32
Q

What do immature DCs do?

A

Uptake and process antigen

33
Q

What do mature DCs do?

A

Present antigen

34
Q

Where are immature DCs located?

A

Peripheral tissues

35
Q

Where are DCs that are processing antigen located?

A

Lymphatic location

36
Q

Where are mature DCs located?

A

Lymphoid tissues

37
Q

What are the 2 models of DC maturation?

A

Classical model

Revised model

38
Q

What happens in the classical model?

A

Pathogen-induced migration

39
Q

What happens in the revised model?

A

Steady state migration

Pathogen induced migration

40
Q

What is pathogen-induced migration?

A

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

41
Q

What is steady state migration?

A

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

42
Q

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

A

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

43
Q

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

A

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

44
Q

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

A

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

45
Q

Why can cross-presentation be done?

A

Because it enhances MHC

46
Q

What is the second exception to antigen presentation?

A

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

47
Q

What are peptides processed through?

A

Proteosomes

48
Q

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

A

Direct presentation

49
Q

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

A

Direct presentation

50
Q

What kind of antigen presentation is viral infection?

A

Cross-presentation

51
Q

What kind of antigen presentation do exogenous viral antigens use?

A

Cross-presentation

52
Q

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

A

Cross-presentation

53
Q

Look at direct and cross-presentation picture

A

Look at direct and cross-presentation picture

54
Q

What can cross presentation explain the direct presentation cannot?

A

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

55
Q

What is dendritic cell nibbling?

A

Cross-presentation

DC meets the infected cell and chops the head off of the infected cell (extracellular uptake)

56
Q

What is autophagy?

A
Presentation of cellular antigens by MHC class II
Self-eating
57
Q

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

A

They multiply quickly and generate multiple clones

58
Q

What are the principal manifestations of immunological autophagy?

A

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

59
Q

What cells express MHC class I?

A
T cells
B cells
Macrophages
DCs
Neutrophils
60
Q

What cells express MHC class II?

A

B cells
Macrophages
DCs
Thymic epithelium

61
Q

What is degenerate binding specificity?

A

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

62
Q

What is the peptide-binding groove?

A

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