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Sem 2: Immuno > Antigen Processing and Presentation - Bittencourt > Flashcards

Antigen Processing and Presentation - Bittencourt Flashcards

1
Q

What do dendritic cells present to?

A

Naive T cells and CD8+ T cells

dendritic cells initiate T cell response

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2
Q

What do macrophages present to?

A

CD4+ cells in the effector stage of cell mediated immunity

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3
Q

What do B cells present to?

A

CD4+ cells during humoral immunity

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4
Q

What are some non professional APCs?

A
  1. Neutrophils
  2. NK cells
  3. T cells
  4. Basophils
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5
Q

What is it called when APCs provide additional stimulus to T cells?

A

Co-stimulation

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6
Q

What is the sequence of events for processing of an endocytosed antigen?

A

MHC II pathway

  1. Uptake of extracellular pathogen
  2. Processing in endosome/lysosome vesicles
  3. Biosynthesis and transport to of MHC II molecules to endosomes
  4. Association of processed peptides with MHC II molecules in vesicles
  5. Expression of peptide-MHC II complex to APC surface to CD4+ T cells
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7
Q

What are the most important proteolytic enzymes involved in protein degradation?

A

cathpesin

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8
Q

What is the variable region of the MHC II molecule?

A

alpha 1 + beta 1 = peptide binding cleft

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9
Q

Where do CD4+ T cells bind to on MHC II molecules?

A

beta 2 non variable region

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10
Q

Where do CD8+ T cells bind to on MHC I molecules?

A

alpha 3 non variable region

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11
Q

What is the variable region of the MHC I molecule?

A

alpha 1 + alpha 2 = peptide binding cleft

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12
Q

Where does the association of processed peptides with MHC II molecules take place?

A

endosomes

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13
Q

Where does proteolytic degradation take place in the MHC I pathway?

A

Proteosomes

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14
Q

In which pathway are proteins ubiquitinated for proteosomal degradation?

A

MHC I pathway

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15
Q

The TAP transport system is involved in which MHC pathway?

A

MHC I

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16
Q

What is the purpose of TAP?

A

mediates the transport of peptides entering into the ER

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17
Q

Exogenously acquired proteins will generate peptides that activate?

A

CD4+ T cells

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18
Q

Endogenously acquired proteins will generate peptides that activate?

A

CD8+ T cells

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19
Q

What is the predominant type of TCR and where is it found?

A

alpha/beta TCR

found in lymphoid tissues

20
Q

Where are yQ TCRs found?

A

in mucosal surfaces

21
Q

Which TCR is MHC dependent?

A

alpha/beta TCR

22
Q

Which TCR is MHC independent?

A

yQ TCR

23
Q

What do most T lymphocytes recognize?

A

Peptides

24
Q

Which T cell recognizes peptides of 8-10 AA ?

A

CD8+ cells on MHC I

25
Q

Which T cells recognize peptides > 13 AA ?

A

CD4+ T cells on MHC II

26
Q

True or False: T cells may be specific for haptens

A

TRUE

27
Q

What is closely associated with the TCR and helps to confirm its ID as a T cell?

A

CD3 complex

28
Q

CD3 complex

A

closely associated to the TCR

transduces activation signals

invariant, doesnt contribute to T cell specificity but is needed to generate a response

29
Q

What is MHC restriction?

A

When T cells only recognize things displayed to them on SELF MHC

Prevents autoimmunity

30
Q

Which receptor is not restricted by MHC presentation?

A

BCR on B cells

31
Q

What do B cells recognize?

A
  1. Peptides
  2. Proteins
  3. Nucleic acids
  4. Polysaccharides
  5. Lipids
32
Q

What are the differences between TCR and BCR’s?

A
  1. BCR has 2 Ag binding sites
  2. BCR does not interact w MHC molecules
  3. B cells can recognize soluble antigens
33
Q

How are lipids presented to T cells?

A

Through CD1 on NKT cells

34
Q

What 2 signals are required for T cell activation?

A
  1. SPECIFIC SIGNAL - where MHC-peptide complex binds to TDR-CD3 complex
  2. CO-STIMULATORY SIGNAL - where CD28 on T cell interacts with B7 (CD80/CD86) on APC
35
Q

What happens when T lymphocytes are stimulated without a co-stimulatory signal?

A

Clonal anergy occurs

A state of no responsiveness, does not generate immune response

36
Q

What are the activating receptors on T cells?

A

CD28 and ICOS

37
Q

What are the inhibitory receptors on T cells?

A

PD-1 and CTLA-4

38
Q

CD28 on CD4+T cells bind to __________ on APC’s

A

B7 (CD80/CD86)

*** costimulatory transduction to activate naive T cells

39
Q

What makes dendritic cells most effective for initiating T cell responses?

A
  1. Located at sites where microbes enter
  2. Expresses high levels of co-stimulatory molecules needed to activate Naive T cells
  3. Captures and transports antigens to draining lymph nodes
40
Q

When do dendritic cells express a lot of co-stimulatory molecules?

A

Once activated

after capturing Ag high co-stimulatory molecules are expressed to activate Naive T cells

41
Q

When do dendritic cells express a lot of Fc and mannose receptors?

A

When resting in tissue waiting to capture Ag

42
Q

Do resting dendritic cells or activate dendritic cells have a longer half life?

A

Activated

43
Q

Macrophages and dendritic cells are inducible by _______

A

IFN-y

44
Q

What do dendritic cells present to CD8+ T cells?

A

infected cells or tumor cells

45
Q

What is cross-presentation / cross - priming?

A

Ability of dendritic cells to present to naive CD4+ T cells and CD8+ T cells

Sem 2: Immuno (17 decks)

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