Linking: Visualizing Antigen presentation

Question 1

T OR F: dcs can only present 1 antigen at a time

Answer 1

False = can present multiple antigens at once

Question 2

Describe sequence of dc activation/T cell activation

Answer 2

PRRs activated in peripheral tissue
Dc gets activated and presents antigen to T cells in lymph node
Doesn’t happen all in same place or time

Question 3

What does entry of T cell into lymph node require

Answer 3

Activated of adhesion moelcuels and chemokines

Question 4

Describe adhesion moelcuels involved in T cell entry into lymph node

Answer 4

Selectins=binding —> allow for rolling
Integrity = binding causes tight binding and lymphocyte to migrate= rolling stops

Question 5

Describe chemokiens involves in T cell entry into lymph node

Answer 5

Chemokine binding chemokine receptor = ccl19 and ccl21 binds to ccr7 (chemokine receptor) on lymphocytes = leads to activation of integrins = changes conf

Question 6

How do t cels enter lymph node

Answer 6

High endothelial venules

Question 7

What are involved in leukocyte homing

Answer 7

Selectins
Light attachment of Selectins on T cells to HEV results in T cell rolling along endothelial surface and targeting them to lymphoid tissue
Depends on secondary organ = diff moelcuels expressed

Question 8

What do diff tissues express

Answer 8

HEV = lymph nodes
Mucosal epithelium = peyers patches
Also adhesion moelcuels diff

Question 9

Name and describe all steps of leukocyte homing = 4 main steps

Answer 9

Rolling = mediated by Selectins (chemokine + receptor, L selectin on T cell, integrin on T cell)
Activation = by chemokines (intracellualr signalling = activation of integrin)
Arrest and tight binding (adhesion): mediated by integrin integration
Diapedesis = transendothelial migration into lymph node

Question 10

What do T cells do once in lymph node

Answer 10

T cells scan for antigen
Sample antigens

Question 11

What do dcs do in lymph node

Answer 11

Can secrete chemokines to attract T cells to them

Question 12

Describe what fibroblastic reticular cells do

Answer 12

Provide roadways for naive T cells =
Secrete ccl19 and ccl21 chemokiens = attract T cells and dcs to lymph node

Question 13

What happens once T cell interacts with ag

Answer 13

Naive T cells arrest movements after engaging in ag:mhc
Stops moving
Slow down movement through lymph node

Question 14

Describe kinetics of T cells and dc interaction

Answer 14

Kinetics = how long it lasts
Kinetics of early encounters depends on quality, quantity, availability of ag and activation state of a dc = if not lock and key Match, if dc will die soon, many diff condition s

Question 15

What is immunological synapse

Answer 15

T cells become involved in commmited long term (8+ hrs) relationships with dendritic cells = immunological synapse

Question 16

Is immunological synapse just between T cells and dcs

Answer 16

No
Between any 2 cells

Question 17

Describe timing of events of T cells

Answer 17

Dc can be surveyed by more than 5000 T cells per hour, many cells, one match = takes time
T cells can spend 1-24 hrs circulating and looking for antigen
T cells can experience proliferation and differentiation over following 4 days

Question 18

Describe immune system dynamics

Answer 18

Balancing generation in primary lymphoid organs with activation, proliferation and differentiation in secondary lymphoid organs

Question 19

Describe immune system dynamics - deals with

Answer 19

Microinury, tissue repair and microbiota = other things we have to deal with

Question 20

Describe immune system dynamics - overlap

Answer 20

Many events happening in parallel
Not linear story
Overlap over time
Can change locations and influence each other

Question 21

Describe immune system dynamics = Specific stages and steps

Answer 21

Innate = production of cytokines = 1-5 days after infection, nk cell mediated killing of infected cells = 1-10+ days
T cell mediated killing of infected cells = 2-10+
Then down reg

Question 22

What is titer

Answer 22

Virus titer = amount of virus

Question 23

What are T cells

Answer 23

Types of lymphocytes

Question 24

Where do T cells arise

Answer 24

In thymus from bone marrow progenitors

Question 25

What requires the activation of T cells

Answer 25

Most adaptive immune responses = basically all of them

Question 26

What can t cells recognize

Answer 26

Only recognize peptide fragments of antigen bound to self molecules of the major histocompatibility complex

Question 27

Where are peptide mhc complexes expressed

Answer 27

On plasma membrane of apcs

Question 28

Describe order of t cell activation

Answer 28

Tcr signallig - peptide on mhc
Costimulatory interaction
Cytokine signalling

Question 29

What do lymphocytes carry

Answer 29

Different sets carry diff clusters of differentiation co receptors on their surface (cd)

Question 30

Describe cd8+ T cells

Answer 30

Become effector cytotoxic t lymphocytes = CTLs

Question 31

Describe cd4+ t helper cells

Answer 31

Can be divided into distinct subsets =
Th1, th2, th17, t reg (regulatory), t fh (follicular helper). = now effector cells
Each produces a distinct cytokine profile and regulates distinct activities within body

Question 32

What do cd8+ T cells recognize

Answer 32

Antigen on mhc I

Question 33

What do cd4+ T cells recognize

Answer 33

Antigen on mhc II

Question 34

What does pamp do - link

Answer 34

Activation signals sent to T cells = highly depends on pamp that dendritic cell exposed to
Will influence cytokines produced = leading to type of effector T cells that will arise (this will also produce diff cytokines)
Ex = helminth, binds tlr1/2 = need th2 to clear this infection