Antigen presentation and processing

Question 1

Dendritic cell antigen uptake mechanism

Answer 1

1. Endocytosis

2. Phagocytosis

Question 2

Dendritic cell activation

Answer 2

Mediated by pattern recognition receptors (PRRs)

Question 3

Dendritic cell MHC class II expression

Answer 3

Increases with activation (may express low levels constiuitively)

Question 4

Dendritic cell costimulatory activity

Answer 4

Up-regualtion of CD80/86 w/activation

Question 5

Dendritic cell T-cell activation

Answer 5

Naive, effector, memory T cells

Question 6

Dendritic cell location

Answer 6

Resting: circulation and peripheral tissues.
Active: T-cell zones, tertiary tissues

Question 7

Macrophage antigen uptake mechanism

Answer 7

Phagocytosis

Question 8

Macrophage activation

Answer 8

Mediated by PRRs and enhanced by T cell help

Question 9

Macrophage MHC class II expression

Answer 9

Increases w/activation

Question 10

Macrophage costimulatory activity

Answer 10

Up-regulation of CD80/86 with activation

Question 11

Macrophage T cell activation

Answer 11

Effector and memory T cells

Question 12

Macrophage location

Answer 12

Resting: circulation, peripheral tissues.
Activated: lymph node, marginal zone of spleen, peripheral tissues

Question 13

B cell antigen uptake mechanism

Answer 13

Receptor-medated endocytosis

Question 14

B cell activation

Answer 14

Mediated by antigen recognition

Question 15

B cell MHC class II expression

Answer 15

Increases with activation (expresses low levels of constitutively

Question 16

B cell costimulatory activity

Answer 16

Upregulation of CD80/86 w/activation

Question 17

B cell T cell activation

Answer 17

Effector and memory T cells

Question 18

B cell location

Answer 18

Resting: circulation, follicles
Activated: B cell/T cell interface, germinal centers and marginal zones

Question 19

Cytosolic pathway

Answer 19

1. Presentation of antigen on class I molecules: good for stopping damaged protein, needs intracellular protein synthesis. Constitutie and immunoproteosome

Question 20

Constitutive proteosome

Answer 20

Normal proteosome. Can give way to immunoproteosome if cell stimulated by IFN-y or TNF-A

Question 21

Immunoproteosome

Answer 21

Activity changes. More efficiently loads class I molecules through better TAP association

Question 22

Where are peptides from the cytosolic pathway transported to? What do they bind to?

Answer 22

The rough endoplasmic reticulum where Class I molecules are synthesized.
Bind to TAP1 and TAP2 heterodimer complex that extends across the RER.

Question 23

TAP

Answer 23

Transpoter associated with antigen processing.
Affinity for 8-16 amino acids.
-Optimal binding size of MHC I is 9.

Question 24

ERAAP

Answer 24

ER-associated aminopeptidase. Does the final trimming of peptides.

Question 25

Where is the MHC class I alpha chain synthesized?

Answer 25

The RER

Question 26

Calnexin

Answer 26

What MHC Class I molecules associate with to assure proper folding

Question 27

What happens once MHC class I alpha chain properly folded?

Answer 27

Associates w/B2-microglobulin and releases calnexin

Question 28

Tapasin (Tps)

Answer 28

Allows for MHC class I association with TAP1/2 complex.

Question 29

Endocytic pathway

Answer 29

-Presentation of antigen on class II molecules. Needs endocytic uptake of exogenous antigen

Question 30

Where does the maturation step of the endocytic pathway take place?

Answer 30

The RER. Binding site will be occluded for a little while

Question 31

What are exogenous antigens internalized as?

Answer 31

APCs through endocytosis or phagocytosis

Question 32

What happens to internalized antigens?

Answer 32

Degraded as phagolysosomes or endosomes

Question 33

How much time is required for the antigen to be processed and presented within the endocytic pathway?

Answer 33

1-3 hours

Question 34

Invariant Chain (CD74)

Answer 34

• Assists in folding of class II alpha and beta chains.
• Binds to the peptide-presenting site of class II molecules.
• Assistin in transport of MHC class II molecules from golgi to cytoplasmic vesicles

Question 35

CLIP

Answer 35

Short fragment that remains after the digestion of the invariant chain. Bound to antigen presenting site on MHC class II molecule

Question 36

HLA-DM

Answer 36

Nonclassical MHC II molecule needed to catalyze exchange of antigenic peptide for CLIP

Question 37

HLA-DO

Answer 37

Can regulate HLA-DM. Blocks HLA-DM (except in really acidic conditions). Only expressed in B cells and thymus. Not induced by IFN-y.

Question 38

Cross presentation of exogenous antigen

Answer 38

Good way to ramp up CD8+ T cell amplification and proliferation