Antigen Processing and Presentation - Bittencourt

Question 1

What do dendritic cells present to?

Answer 1

Naive T cells and CD8+ T cells

dendritic cells initiate T cell response

Question 2

What do macrophages present to?

Answer 2

CD4+ cells in the effector stage of cell mediated immunity

Question 3

What do B cells present to?

Answer 3

CD4+ cells during humoral immunity

Question 4

What are some non professional APCs?

Answer 4

1. Neutrophils
2. NK cells
3. T cells
4. Basophils

Question 5

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

Answer 5

Co-stimulation

Question 6

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

Answer 6

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

Question 7

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

Answer 7

cathpesin

Question 8

What is the variable region of the MHC II molecule?

Answer 8

alpha 1 + beta 1 = peptide binding cleft

Question 9

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

Answer 9

beta 2 non variable region

Question 10

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

Answer 10

alpha 3 non variable region

Question 11

What is the variable region of the MHC I molecule?

Answer 11

alpha 1 + alpha 2 = peptide binding cleft

Question 12

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

Answer 12

endosomes

Question 13

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

Answer 13

Proteosomes

Question 14

In which pathway are proteins ubiquitinated for proteosomal degradation?

Answer 14

MHC I pathway

Question 15

The TAP transport system is involved in which MHC pathway?

Answer 15

MHC I

Question 16

What is the purpose of TAP?

Answer 16

mediates the transport of peptides entering into the ER

Question 17

Exogenously acquired proteins will generate peptides that activate?

Answer 17

CD4+ T cells

Question 18

Endogenously acquired proteins will generate peptides that activate?

Answer 18

CD8+ T cells

Question 19

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

Answer 19

alpha/beta TCR

found in lymphoid tissues

Question 20

Where are yQ TCRs found?

Answer 20

in mucosal surfaces

Question 21

Which TCR is MHC dependent?

Answer 21

alpha/beta TCR

Question 22

Which TCR is MHC independent?

Answer 22

yQ TCR

Question 23

What do most T lymphocytes recognize?

Answer 23

Peptides

Question 24

Which T cell recognizes peptides of 8-10 AA ?

Answer 24

CD8+ cells on MHC I

Question 25

Which T cells recognize peptides > 13 AA ?

Answer 25

CD4+ T cells on MHC II

Question 26

True or False: T cells may be specific for haptens

Answer 26

TRUE

Question 27

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

Answer 27

CD3 complex

Question 28

CD3 complex

Answer 28

closely associated to the TCR transduces activation signals invariant, doesnt contribute to T cell specificity but is needed to generate a response

Question 29

What is MHC restriction?

Answer 29

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

Question 30

Which receptor is not restricted by MHC presentation?

Answer 30

BCR on B cells

Question 31

What do B cells recognize?

Answer 31

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

Question 32

What are the differences between TCR and BCR's?

Answer 32

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

Question 33

How are lipids presented to T cells?

Answer 33

Through CD1 on NKT cells

Question 34

What 2 signals are required for T cell activation?

Answer 34

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

Question 35

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

Answer 35

Clonal anergy occurs A state of no responsiveness, does not generate immune response

Question 36

What are the activating receptors on T cells?

Answer 36

CD28 and ICOS

Question 37

What are the inhibitory receptors on T cells?

Answer 37

PD-1 and CTLA-4

Question 38

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

Answer 38

B7 (CD80/CD86) *** costimulatory transduction to activate naive T cells

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

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

Answer 41

When resting in tissue waiting to capture Ag

Question 42

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

Answer 42

Activated

Question 43

Macrophages and dendritic cells are inducible by _______

Answer 43

IFN-y

Question 44

What do dendritic cells present to CD8+ T cells?

Answer 44

infected cells or tumor cells

Question 45

What is cross-presentation / cross - priming?

Answer 45

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