Adaptive Immunity, MHC, B-Cells, T-Cells (complete)

Question 1

What are the three main ways that adaptive immunity is different from innate immunity

Answer 1

1. instead of a limited number of receptors, lymphocytes have 1 receptor will nearly infinite possibilities
2. delayed onset, a few days
3. immune memory = next exposure is better/faster

Question 2

how many type of receptors does each t cell have

Answer 2

1

Question 3

What is the MHC

Answer 3

major histocompatibility complex

Question 4

what are the two types of MHCs

Answer 4

class 1 antigens
class 2 antigens
(there are also class 3, but they aren't as important to immunity)

Question 5

where do you find class 1 MHCs

Answer 5

almost all nucleated cells

Question 6

where do you find class 2 MHCs

Answer 6

only in APCs (antigen presenting cells)

Question 7

what do class 1 MHCs do

Answer 7

hold a peptide fragment from an intracellular protein to present it to a T-cell (cytotoxic T-cell, CD8)

Question 8

what do class 2 MHCs do

Answer 8

hold a peptide fragment from an extracellular protein to present it to a T-cell (helper T-cell, CD4)

Question 9

which class of MHC works on endogenous antigens, and which class of MHC works on exogenous antigens

Answer 9

class 1 works with endogenous antigens
class 2 works with exogenous antigens

Question 10

what two things can the presentation of endogenous peptides from MHC class 1s tell you about the cell

Answer 10

1. it can show “self” proteins and show that the cell is self
2. it can show viral proteins and show that the cell has been infected

Question 11

what does the presentation of exogenous peptides from class 2 MHCs tell you

Answer 11

it is only on cells involved in the immune response, and helps target things that shouldn’t be in our systems

Question 12

From where do you get peptides that class 1 MHC’s present, and who do they specifically present them to?

Answer 12

they come from the cytosol and “talk” to Cytotoxic T-cells

Question 13

from where do you get the peptides that class 2 MHCs present, and who do they specifically present them to>

Answer 13

they come from endosomal compartments (exogenous) and are taken from there to the cell surface by MHC class 2s. they “talk” to Helper T-cells

Question 14

what is the human analog of MHC

Answer 14

HLA

Question 15

what are immature dendritic cells like

Answer 15

• effective phagocytes
• low class 1 MHC
• no class 2 MHC
• recognize cytokines

Question 16

what are mature dendritic cells like

Answer 16

• less phagocytotic activity

- high MHC levels (both classes)

Question 17

How do dendritic cells mature

Answer 17

1. on their own (spontaneous maturation)

2. by phagocytosing a microbe

Question 18

do spontaneously matured dendritic cells activate naive T-cells

Answer 18

nope

Question 19

do activated matured dendritic cells activate naive T-cells

Answer 19

yes, maybe the only thing that can do so effectively

Question 20

how do matured Dendritic cells activate naive-t cells

Answer 20

1. microbes and macrophages cause IL-1 and TNF
2. IL-1 and TNF cause mature dendritic cells to migrate to secondary lymphoid structures
3. they express high levels of MHC, B7-1 and B7-2
4. those interact with CD4 T-cells
   (need the T-cell to bind BOTH the MHC, and the B7s)

Question 21

what is important in determining compatibility of tissue grafts

Answer 21

MHCs

Question 22

what makes dendritic cells hone to secondary lymphoid tissue

Answer 22

CCR7

Question 23

what on naive T-cells looks for the B7-1 and B7-2 on activated mature dendritic cells

Answer 23

CD28

Question 24

how do the peptide grooves of MHC class 1 and 2 molecules differ

Answer 24

class 1  has capped ends and only allows shorter peptides. it also uses one protein as both sides of the binding groove
class 2 doesn't have capped ends and can allow longer peptides. it uses two separate proteins as the sides of the binding groove

Question 25

are all MHC class ones the same

Answer 25

no, there are many different class 1 MHCs ( the same for class 2 MHCs) thats why they can cause problems in acceptance of a grafted tissue

Question 26

what is the most gene dense region of the human genome

Answer 26

the MHC gene region

Question 27

how are MHC alleles expressed

Answer 27

codominantly (both the mom and dads MHCs are expressed)

Question 28

if a human and mouse have three MHC 1 proteins, how many different MHC 1’s can they have on a given cell

Answer 28

6
Ad
Am
Dd
Dm
Ld
Lm

d= from dad
m = from mom

Question 29

if a human has three MHC class 2 proteins (a dimer) how many different MHC 2s can they have on a given cell

Answer 29

12

Question 30

if a mouse has three MHC class 2 proteins (a dimer) how many different MHC 2s can they have on a given cell

Answer 30

8

Question 31

if some species is found to have 4 MHC class 2 proteins (a dimer) how many different MHC 2s could they have on a given cell

Answer 31

16
(5 = 20)
(6=24)

Question 32

what do classical MHCs do?

what do non-classical MHCs do

Answer 32

classical present peptide antigens to T-cells

non-classical do anything else

Question 33

where do you find the polymorphisms in class 1 and 2 MHCs

Answer 33

in the peptide binding grooves

Question 34

what helps the intermediate immune response between innate and adaptive immunity

Answer 34

non-classical MHCs

Question 35

what is CD1

Answer 35

a non-classical MHC that presents mycobacterial glycolipids to specialized T-cells

Question 36

what enzyme creates the endogenous peptides that are presented by class 1 MHCs

Answer 36

proteasomes

Question 37

what is the process of creating peptides that MHC class 1s will present to cytotoxic CD8 t-cells

Answer 37

1. ubiquitin tags the intracellular protein
2. Proteasomes cleave the peptide in the cytosol
3. peptidem moves into the ER lumen
4. it binds to MHC 1 and this creates a vesicle
5. then it is transferred to the cell membrane

Question 38

what is the difference between constituative proteasomes and immunoproteasomes

Answer 38

immunoproteasomes cut peptides into better lengths for MHC class 1s

Question 39

what are DRiPs and how do they relate to MHCs

Answer 39

they are defective ribosomal products, and they are usually marked by ubiquitin and cut up by proteasomes, then bound to MHC1 and sent to the membrane

Question 40

what happens to MHC1s that don’t bind a peptide in the ER

Answer 40

they are broken down eventually

Question 41

how can viruses counteract their destruction by MHC1s

Answer 41

they can stop the process of MHCs binding peptides, and moving to the membrane, so cytotoxic T-cells don’t attack them

Question 42

how does herpes virus prevent being killed by cytotoxic t-cells

Answer 42

they stop the MHC 1 from binding peptides and moving to the surface

Question 43

how does the body kill cells that have overcome the MHC1s ability to signal for their destruction

Answer 43

NK cells can recognize the low MHC class 1 levels and will destroy the cell

Question 44

what do helper T-cells do once they have been presented the peptide fragment from MHC class 2

Answer 44

1. they show it to macrophages (this activates them to be more efficient killers)
2. they show it to B-cells (this causes them to differentiate and expand into plasma cells, these create antibodies)

Question 45

how are class 2 MHC’s loaded with peptides

Answer 45

1. MHC 2 in ER is blocked by invariant chain
2. in a vesicle the invariant chain degrades, leaves CLIP fragement
3. Exogenous antigen is taken up
4. HLA-DM switches the antigen and CLIP
5. it is transported to the membrane

Question 46

what on the T cells helps recognize the MHCs that are presenting peptides to them

Answer 46

1. TCR (T-cell receptor)
2. either CD8 or CD4
   (if CD8 = cytotoxic T-cell, binds MHC 1)
   (if CD4 = helper T-cell, binds MHC 2)

Question 47

what to TAPS do

Answer 47

takes the peptides from the proteasomes and puts them back into the ER, and binds them to the MHC

Question 48

what is cross presentation of exogenous antigens

Answer 48

exogenous antigens that are redirected into the enogenous presentation pathway. exogenous peptides with MHC class 1.

Question 49

what cells do cross presentation of exogenous antigens

Answer 49

dendritic cells

Question 50

what does cross presentation of exogenous antgens do

Answer 50

causes CD8 cytotoxic t-cells to be primed by exogenous antigens (instead of endogenous)