Immuno Week 2 post lect. updates

Question 1

Why is important that MHC proteins are very general in what they bind?

Answer 1

It they were specific then we would have to produce way more MHC proteins to bind all potential antigens, instead we just leave it up to the T cells to figure it out

Question 2

Which of the MHC molecules is more diverse?

- what is the main contributing factor to this diversity?

Answer 2

MHC class II is more diverse, this can be attributed mainly to the fact that they have BOTH alpha and beta genes that can combine in different ways

Question 3

What does loss of CLIP/ invariable chain lead to?

Answer 3

Loss of ability to distinguish between intracellular and extracellular pathogens

Question 4

Why are MHC proteins so important in organ rejection?

Answer 4

Largest degree of polymorphisms in genome means its unlikely to find people whose MHC profiles are identical

Question 5

What between MHC I and II which is the most likely target for transplant rejection?

Answer 5

MHC I because its located throughout the body

Question 6

What determines your BO and why are you attracted to people with BO that is different from yours?

Answer 6

MHC haplotype determines BO, and it is evolutionarily advantageous for us to mate with people who have haplotypes that are different than ours.

Question 7

MHC I proteins exist on all cells but they are more strongly represented on APCs. Why is this so?

Answer 7

APCs must enter secondary tissue for a response to be mounted because the correct T cell is most likely located there.
Also APCs have B7 which is needed to activate niave T cells

Question 8

What affect does lack of TAP1/2 have on MHC profile of cells?

Answer 8

No TAP1/2, then no proteins are loaded the MHC class I and they will be degraded

Question 9

What would be bad about upregulating the amount of CTLA-4 on naive T cells?

Answer 9

CTLA-4 would reduce T naive cell activation. This is advantageous for things like cancers

Question 10

T or F: you need less MHC class II binding to reach the threshold.

Answer 10

True

Question 11

What is the most important interaction for getting naive cells into 2˚ lymph tissue?

Answer 11

L-selectin to GlyCam-1, this expression is lost on activated T cells which keeps them out of 2˚ lymph

Question 12

What interaction lets neutrophils out of vascular endothelium into extravascular space?

Answer 12

PECAM-1:PECAM-1 (CD-31:CD-31) interaction

Question 13

What is IL-8 also known as and what is its function?

Answer 13

AKA CXCL8, it binds neutrophils to slow them down

Question 14

What will happen to your ability to form germinal centers if you have to B cells?

Answer 14

If you don’t have any B-cell, then you will be unable to form Germinal centers.

Question 15

T or F: IL-22 and IL-17 are chemotractants secreted by T17 cells

Answer 15

False

IL-17 INDUCES endothelial cells to produce a neutrophil chemotractant

IL-22 INDUCES endothelial cells to produce and antibacterial peptide

Question 16

Is Treg considered an effector cell?

- why or why not?

Answer 16

NO, it requires B7 co-stimulation

Question 17

T or F: Tregs are found in the greatest proportions in the blood to prevent cytotoxic cells from reacting to host proteins

Answer 17

False, Treg are found in SECONDARY LYMPH. tissues

• They need to be located here to be in contact with macrophages and prevent proliferation of naive T cells that react to self antigen

Question 18

T or F: when Treg down regulates, it must be recognizing the same antigen as the cell that it is suppressing

Answer 18

False, there are many antigen types that are presented on a macrophage so it is unlikely they will be bound to the same antigen. BUT if there’s a lot of Treg bound to a macrophage, it has probably ingested host material and most presented antigens will be self-antigens, so any effector cell that binds is probably one the snuck by during negative selection and its proliferation should be limited.

Question 19

What are the 3 things the NK cells look for when going out to kill cells?

Answer 19

1. Amount of MHC class I- if you lack MHC class I, you will be killed
2. MIC - presence of MIC indicates stress and NK will kill that cell
3. IgG1 and IgG3, NK cells see these and kill any cell with these bound (opsonization aka ADCC)

Question 20

T or F: NK cells are good at clearing out intracellular bacterial infections

Answer 20

False

Question 21

What is the link between TH1 responses and activation of NK cells?

Answer 21

TH1 response leads to the formation (via B cell activation) of opsonizing types of antibodies (IgG1 and IgG3), these are detected by NK cells which will then kill them

Even though TH1 is responsive to intracellular pathogens the NK cells really only get fired up during viral infections

Question 22

What does GM-CSF do?

Answer 22

Simulates bone marrow to make more macrophages and neutrophils

Question 23

T or F: BOTH IFN-gamma and CD-40 are needed for macrophage activation

Answer 23

True

Question 24

Besides macrophage activation, what does CD40 act to do?

Answer 24

Both TH1 and TH2 need it to activate B cells

Question 25

T or F: T cells are needed for granulomas to form

Answer 25

True

Question 26

Why does CD8+ T cell response to an intracellular infection also trigger a TH1 response?

Answer 26

No matter what there will always be some cross presentation of antigens so some of the MHC class II that is for extracellular antigen will present some intracellular peptides leading to TH1 cells getting upregulated

Question 27

What is the main function of TH2?

- what does it use to do this?

Answer 27

Drives B cells to make neutralizing antibodies (IgA, IgE, IgG2, and IgG4)

IL-4 stimulates IgE formation via class switching
IL-5 stimulates IgA formation via class switching

Question 28

T or F: IL-2 is required for B cell mediated response (humoral) and for cell mediated response.

Answer 28

True