Lecture 15 - Antigen-Presenting Cells II Flashcards Preview

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Flashcards in Lecture 15 - Antigen-Presenting Cells II Deck (29):
1

Prototypical mediators of DC activation and maturation

TLRs

2

Do activated DCs move actively or passively to lymph nodes?

Actively

3

DCs in the epithelium of the skin

Langerhans cells

4

How do Langerhans cells sit in the skin?

Intimately associated with keratinocytes, to keep skin integrity (associate with E-cadherin).

5

How do activated Langerhans cells reach lymph nodes?

Express CCR7

CCR7 detects chemokines CCL19, CCL21.

6

Which part of lymph nodes do activated DCs move to?

Paracortex

7

How do naive T cells enter lymph nodes?

Via blood, through the walls of high endothelial venules

8

How do DCs enter lymph nodes?

Via lymphatics

9

Where are tumour antigens presented?

MHCI

10

NFkB dimer stimulated by TLR binding

p50, p65

11

How do DCs detect intracellular bacteria?

Inflammosomes

12

How do DCs detect facultative intracellular bacteria?

Surface via TLR5
Endosome via TLR3, TLR11

13

How do DCs detect viruses?

Extracellular or engulfed - TLR3, TLR9 in phagosome
Intracellular - Inflammasome, MDA5, RIG1

14

Basic overview of DCs
1)
2)
3)

1) Mostly exist in immature state of high phagocytic activity, low presentation
2) Possess a wide array of PRRs to integrate environmental cues
3) Stimulation initiates maturation, lowers phagocytosis, increases presentation, migration to lymph node

15

Surface chemokine receptor expressed by mature DCs

CCR7

16

How is MHCI/peptide complex transported to cell surface?

Via Golgi

17

What is DC cross-presentation?

Extracellular, phagocytosed antigens being presented on MHCI, to stimulate CD8+ T cells

18

Why is cross-presentation used?
1)
2)

1) If a virus kills DCs, so DCs need to present to CD8+ T cells without being infected (need infection to present on class I by direct pathway)
2) If a virus is present in the periphery where there are no naive CD8+ T cells (EG: herpes simplex). DCs can take up antigen, present on MHCI and travel to lymph nodes.

19

DC surface proteins expressed upon activation for T cell activation

CD80, CD86

20

How are DCs stopped from eliciting a T cell response against self antigens?
1)
2)

1) CD80 and CD86 are only upregulated if a foreign antigen stimulates PRRs.
2) CD80, CD86 needed to stimulate a T cell. Even if a T cell is cognate with DC presenting a self antigen, without CD80/CD86, nothing will happen

21

Types of antigens presented through cross-presentaiton

Viral antigens

22

Pathogen presented from receptor-mediated endocytosis

Extracellular bacteria

23

Pathogen presented from macro-pinocytosis

Extracellular bacteria, soluble antigen, viral antigen

24

Signal 1, 2 and 3

1) TCR - MHC interaction
2) CD80/CD86 - CD28 interaction
3) Cytokines to bias T cell type

25

Signal 1 role

Activation of T cell

26

Signal 2 role

Survival of T cell

27

Signal 3 role

T cell differentiation

28

Do activated CD8+ T cells need a signal 2?

No.
They will be in the periphery, killing non-professional APCs, which can't costimulate

29

Type of T cell that doesn't require signal 2

Activated CD8+ T cell