Antigen presentation and the MHC

Question 1

Location of macrophages

Answer 1

Blood, liver, spleen

Question 2

location of dendritic cell

Answer 2

Skin, lymphoid tissues

Question 3

Location of B cells

Answer 3

Lymphoid tissues, infection sites

Question 4

Macrophages in the different parts of the body

Answer 4

Microglia in the brain, Kupffer cells in the liver

Question 5

Skin APCs

Answer 5

Langerhans cells, which line the junction of the dermis and epidermis

Question 6

How do skin APCs help the immune response?

Answer 6

They travel to the paracortex and present to the T cells there

Question 7

Plasmacytoid dendritic cells

Answer 7

Produce large quantities of interferon in response to viral infections

Question 8

Conventional dendritic cells

Answer 8

Undergo a maturation process

Question 9

From what are antigenic peptides usually derived on an MHC I molecule?

Answer 9

Viruses that have taken over the cell

Question 10

How are invaded viruses made into antigens?

Answer 10

Proteosomes in the cell degrade them and put them on the MHC (subunits LMP2 and LMP7)

Question 11

Transport of peptides to the MHC

Answer 11

Transported by TAP-1 and -2

Question 12

ER antigen chaperones

Answer 12

Erp57, calnexin, calreticulin

Question 13

What is the purpose of ER chaperone proteins?

Answer 13

Blocks the MHC from being bound by anything other than its antigen

Question 14

ERAAP

Answer 14

Removes the chaperone proteins and allows the binding of the antigen to MHC in the endoplasmic reticulum

Question 15

After the antigen is attached in the ER, what happens?

Answer 15

The antigen complex moves through the golgi body, is put into a vesicle, and transported to the cell surface

Question 16

From what are MHC class II antigens derived?

Answer 16

The products of degradation from phagocytosed substances

Question 17

What is the associated protein with MHCII?

Answer 17

Ii

Question 18

How is Ii removed from the complex?

Answer 18

Acidification

Question 19

What is left in Ii’s spot after acidification?

Answer 19

CLIP

Question 20

What loads/unloads CLIP from the complex?

Answer 20

DM

Question 21

What is displayed in the MHC complexes when there is no foreign antigen?

Answer 21

Class I: self antigen

Class II: CLIP

Question 22

Th1 cells

Answer 22

Activate macrophages

Question 23

Th2 cells

Answer 23

Induce antibody synthesis

Question 24

B7

Answer 24

Also known as CD80 or CD86; co-stimulatory molecule on APCs

Question 25

What are the two signals necessary for activation of T cells?

Answer 25

Binding to the MHC and also the interaction of B7 with CD28

Question 26

Why would an APC not express B7?

Answer 26

When they take up antigens that are not microbial, they don't always express B7

Question 27

What happens when B7 is not expressed?

Answer 27

When T cells recognize the MHC on an APC, they stimulate the APC to express CD40, which binds to the CD40L on the T cell and takes the place of the B7/CD28 interaction

Question 28

What is the interaction between B7 and CD28?

Answer 28

CD28 cleaves B7 and then induces T cell proliferation and differentiation

Question 29

What stimulates the B cell to make B7?

Answer 29

Presence of the antigen on the MHC

Question 30

What happens after MHC-peptide engagement?

Answer 30

TCR initiates a phosphorylation cascade that triggers a lot of branching pathways

Question 31

Time course of MHC-peptide engagement

Answer 31

If bound for a short period of time, killer T execution will be activated; however, complex functions like T cell proliferation take a connection that lasts minutes-hours

Question 32

Mature immunological synapse

Answer 32

Specific pattern of receptor recognition with a central cluster of TCRs surrounded by a ring of adhesion molecules

Question 33

Intermediate ring

Answer 33

Enriched with adhesion molecules like LFA-1 and ICAM-1 that promote efficient TCR-MCH-peptide interaction and lead to a biological response

Question 34

Location of ICAM-1 and LFA-1

Answer 34

LFA-1: T cell surface | ICAM-1: APC surface

Question 35

Inner circle

Answer 35

TCR, CD4, and co-stimulatories