Antigen Presentation and Processing--Diebel

Question 1

Which proteins function to move antigen into lumenal side of RER?

Answer 1

TAP1/2

Question 2

What is a normal CD4:CD8 ratio?

Answer 2

2:1

Question 3

What induces viral 20S proteasome?

Answer 3

INF-gamma, TNF-alpha

Question 4

MHC and costimulatory molecule presentation when on these cells:

APCs

Mononuclear phagocytic cells

B-cells

Answer 4

APC: constitutive expression of MHC and costimulatory molecules, esp. CD28

Mononuclar cells: induced expression of MHC and costimulatory molecules, esp. CD28

B-cells: constitutive expression of MHC molecules and induced expression of costimulatory molecules, esp. CD28

Question 5

NK-cells come from which cell line?

Answer 5

lymphoid progenitors

Question 6

Calnexin

Answer 6

holds MHC-I in RER until it is stimulated

Question 7

CD40–CD40L

2 functions

Answer 7

1. promote class switching with CD4+ T-cells and B-cell interaction
2. stimulates dendritic cell to cross present on MHC-I as well as MHC-II

Question 8

This cousin of CD28 dampens T-cell response

Answer 8

CTLA-4

Question 9

MOA CTLA-4

Answer 9

CTLA-4 binds B7 and dampens immune response

CTLA-4 deficiency leads to fulmination of immune response, uncontrolled

Question 10

What occurs when CD28 is absent and TCR binds MHC complex?

Answer 10

Anergy

if CD28 is absent

Question 11

What stimulates immunoproteosome expression?

Answer 11

IFN-γ and TNF-α

Question 12

What molecule is reponsible for bringing protein fragments from cytosol into RER?

Answer 12

TAP1/2

“transporter associated w/ antigen processing”

Question 13

TAP1/2 bind fragments ideally this long

Answer 13

8-16 amino acids

Question 14

This molecule loads MHC-I molecules

Answer 14

ERAAP

ER-associated aminopeptidase

Question 15

CD4:CD8 normal ratio

Answer 15

2:1

Question 16

If a patient has an MHC-I defect, why do they present with a deficiency in CD8+ T-cell defiency?

Answer 16

(back to thymus)

MHC-I presentation in thymus is also poor

positive selection cannot occur

double positive cells become CD4+ instead because MHC-II is present

Question 17

Flow cytometry detects

Answer 17

cell surface markers

Question 18

What is the function of the CLIP protein?

Answer 18

holds MHC-II open until antigen kicks it out and binds

Question 19

MHC-II

CLIP

CD74

Answer 19

CD74 is invariant chain

CD74 binds antigen pocket of MHC-II

CD74 clipped to form CLIP in endosome

CLIP kicked out by antigen

loaded MHC-II

Question 20

Which presents earlier, CD8+ deficiency or CD4+ deficiency?

Answer 20

CD4+

infancy opposed to early adulthood

Question 21

What replaces CLIP with antigen on MHC-II molecules?

Answer 21

HLA-DO and HLA-DM

(non-classical)