(09) Antigen Presentation

Question 1

1. What encodes molecules used to present processed antigens to T cells?
2. What does endogenous Ag correspond to?
3. Exogenous?

Answer 1

1. MHC
2. MHC class I, cytotoxic T cell (CD8)
3. MHC class II, Helper T cell (CD4)

Question 2

(MHC)

This system functions to recognize a wide variety of epitopes…

1. _____ - several genes exist for a given MHC class
2. _____ - a large number of alleles exist for a given gene
3. _____ - will bind a range of similar epitopes
4. MHC molecules present processed Ag to what?

Answer 2

1. polygenic
2. polymorphic
3. promiscuous
4. T cells

Question 3

What are the sites called in the MHC where alot of mutation occurs?

Answer 3

• MHC ARS hypermutation sites

Question 4

(MHC restriction)

1. A given T cell recepotr will only recognize Ag presented by what?
2. Will T cells educated in one MHC allele/epitope interact with any old APC? What does APC need to express?

Answer 4

1. a particular (self) MHC molecule
2. no; needs to express that allele bearing the same epitope

Question 5

1. Any molecule capable of inducing antibody generation
2. Also called an antigenic determinant, it is the portion of a larger antigenic molecule that is recognized by antibodies or T cell receptor
3. The degradation of proteins into peptides that can bind MHC molecules for presentation to T cells.
4. The display of antigens as peptide fragments bound to MHC molecules on the surface of a cell
5. Highly specialized cells that can display processed antigen as peptide fragments on the cell surface.

Answer 5

1. antigen
2. epitope
3. antigen processing
4. antigen presentation
5. antigen-presenting cells

Question 6

(Antigen Processing and Presentation)

1. What 4 big things are needed?

What does each of these (or belongs in the group)

(phagocytic cells)

2. name 3

(means for degradation of larger molecules)

3. name 2

(Molecules to present peptide fragments onf cell surface)

4. name 1

(Specific receptors to distinguish foreign epitopes)

5. name 1

Answer 6

1. phagocytic cells, means for degradation of larger molecules, molecules to present peptide fragments on cell surface, specific receptors to distinguish foreign epitopes
2. macrophages, dendritic cells, b cells
3. proteosomes (endogenous Ag), phagolysosomes (exogenous Ag)
4. MHC
5. T cell receptors

Question 7

take a gander at this for a spell

Question 8

(MHC class I pathway)

1. Utilizes mostly what molecules for degradation? What does this provide? no requirement to do what? What is included?
2. Proteosome degrades proteins into peptides of what size? How many proteosomes in cells? What are they? Which terminus is defined first?
3. TAP proteins move peptide fragments into what? processing completed by what? Used what as a template?
4. Will MHC leave ER without antigen bound?

Answer 8

1. newly-synthesized; rapid sampling of all interal proteins; retrieve protein from compartments; cryptic peptides
2. 12-15 AA; 2; 20S proteosome and immunoproteosome (has subs); c-terminus
3. ER; aminopeptiase; MHC molecule
4. no

Question 9

(Antigen Presentation - Endogenous Source)

Learn this

1. If the Ag is foreign, what occurs?

Answer 9

1. t cytotoxic cells are activated and kill the host cell

Question 10

(Antigen Presentation - Exogenous Source)

1. Time and energy dependent process which occurs only where?
2. Mononuclear phagocyte system includes 3 things - what are they?
3. Does phagocytosis occur constitutivlely as a normal homeostatic mechanism?
4. Ag prensentation is the link between what?

Answer 10

1. inside of phagocytic cells
2. macrophages, B cells, and dendritic cells (neutrophils are rarely APC and at low efficiency)
3. yes
4. innate and humoral (specific)

Question 12

(MHC class II pathway)

1. Once the phagolysosome matures - contents are degraded by what (two subgroups).
2. Lysosomes containing MHC class II molecules fuse with what?
3. MHC-peptide complex moves to where?
4. When are most of the contents excreted from the cell?

Answer 12

1. proteolytic enzymes (cathepsins and endopeptidases)
2. the endosome
3. the surface of the cell
4. when the phagolysosome fuses with the cell membrane to empty its contents

Question 13

What needs to be in endosomes to break down larger proteins (in MHC type II)?

Learn this (but not to well)

Answer 13

• enzymes

Question 14

(Receptors for Phagocytosis)

1. Do macrophages, b cells, dendritic cells, and meutrophils have overlapping sets of receptors for phagocytosis?
2. What do many recognize?

Answer 14

1. yes
2. opsonins (such as Ab), complement, or acute phase proteins

Question 15

1. If he says Antigen presenting cells - what three is he talking about?
2. What is their technical name?
3. How are macrophages unique?
4. Dendritic cells?
5. B cells?

Answer 15

1. Dendritic cells, macrophages, and B cells
2. Professional APC
3. lots in tissues, respond quickly, make cytokines
4. gobble things up in periphery, mobile, go back to draining lymph nodes (where most T and B cells are)
5. get ahold of antigens, talk to t cells to get activated

Question 16

(APC and T cell activation)

(APCs receive singals that increase functional competence)

1. what increases
2. what are expressed
3. what is induced or inhibited?
4. expression of what is stimulated?

(Signals are receptor derived)

Toll-like receptors, cytokine receptors, and FcR

Answer 16

1. MHC class I/II
2. co-stimulatory molecules
3. migration
4. cytokine expression

Question 17

1. T cells are activated by their interaction with what?
2. where does this occur?

Answer 17

1. with APC through the MHC-T cell receptor complex
2. In secondary lymphoid organs

Question 18

(Macrophages)

1. They are highly four things - what are they?

Answer 18

1. phagocytic (present processed antigens to CD4 T cells)
2. secretory (cytokines)
3. activational (respond quickly to changes in microenvironment)
4. polymorphic (based on tissue site)

Question 19

Learn this

Most of the phagocytosis they do is through their what?

Answer 19

antibodies on the surface of the cell

Question 20

(Antigen Presenting - Dendritic cells)

1. What are the most potent stimulators of naive T cells?
2. Found primarily where?
3. Called what in T cells area?
4. In B cell area?
5. Efficiently take up what, then shed what for uptake and processing by B cells?
6. Found in low numbers in skin, spleen, and blood
7. Upon taking up Ag and with proper stimulation, where do they migrate to? What happens there?

Answer 20

1. dendritic cells
2. lymphoid tissues
3. interdigitating
4. follicular
5. immune complexes; immune complex bodies (exosomes) for uptake and processing by B cells
6. migrate to draining lymph nodes, become less phagocytic and increase expression of MHC class II molecules for interaction with T cells

Question 21

Dendritic cell movement is regulated by what?

Answer 21

• chemokine receptor expression

Question 22

1. Dendritic cells can shed what containing the antigen?
2. B cells take up antigen via specific recongition by what?

Answer 22

1. exosomes (iccosomes)
2. specific IgM

Question 23

1. Can some dendritic cells activate CD8+ T cells?
2. What does this require?
3. What is the process called?
4. Basically processed antigen can be presented as MHC class II or MHC class I - if you have a viral infection in mucosa the dendritic cells can move it
5. So will CD8 kill the dendritic cell?

Answer 23

1. yes
2. class I presentation of exogenous antigens
3. cross-presentation (and retrotranslocation)
4. no - maybe eventually - but it will proliferate a bunch first

Question 24

(Dendritic cells)

1. What does activation of T cell by the APC require?
2. Will signals though the T cell recepotor only (without co-stimulation) initiate adaptive immunity? Is this true for all APC?
3. What is the second signal delivered by?

Answer 24

1. binding to the TCR, plus additional ligand-receptor engagements (co-stimulatory molecules)
2. no; yes
3. additional cell surface structures that are expressed by activated APC

Question 25

(MHC-TCR interactions) 1. What provide the structural component that allows communication with antigen-specific T cells to elicit an immune response? 2. Are there different types of T cells that each best drive certain aspects of an immune response? using what? 3. Different types of T cells provide different functions in immunity, help, or cytotoxicity

Answer 25

1. MHC molecules 2. yes - cytokines 3.

Question 26

(Differentiation of Th cells) 1. There are more defined Th cell subsets into which a Th0 cell can differentiate, depending on what? 2. When does this occur? memorize the middle 3 (but not transcription factors!)

Answer 26

1. the cyotkines encountered 2. initial priming of naive T cells when they interact with an APC