Linking: Visualizing Antigen presentation Flashcards
T OR F: dcs can only present 1 antigen at a time
False = can present multiple antigens at once
Describe sequence of dc activation/T cell activation
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
What does entry of T cell into lymph node require
Activated of adhesion moelcuels and chemokines
Describe adhesion moelcuels involved in T cell entry into lymph node
Selectins=binding —> allow for rolling
Integrity = binding causes tight binding and lymphocyte to migrate= rolling stops
Describe chemokiens involves in T cell entry into lymph node
Chemokine binding chemokine receptor = ccl19 and ccl21 binds to ccr7 (chemokine receptor) on lymphocytes = leads to activation of integrins = changes conf
How do t cels enter lymph node
High endothelial venules
What are involved in leukocyte homing
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
What do diff tissues express
HEV = lymph nodes
Mucosal epithelium = peyers patches
Also adhesion moelcuels diff
Name and describe all steps of leukocyte homing = 4 main steps
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
What do T cells do once in lymph node
T cells scan for antigen
Sample antigens
What do dcs do in lymph node
Can secrete chemokines to attract T cells to them
Describe what fibroblastic reticular cells do
Provide roadways for naive T cells =
Secrete ccl19 and ccl21 chemokiens = attract T cells and dcs to lymph node
What happens once T cell interacts with ag
Naive T cells arrest movements after engaging in ag:mhc
Stops moving
Slow down movement through lymph node
Describe kinetics of T cells and dc interaction
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
What is immunological synapse
T cells become involved in commmited long term (8+ hrs) relationships with dendritic cells = immunological synapse
Is immunological synapse just between T cells and dcs
No
Between any 2 cells
Describe timing of events of T cells
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
Describe immune system dynamics
Balancing generation in primary lymphoid organs with activation, proliferation and differentiation in secondary lymphoid organs
Describe immune system dynamics - deals with
Microinury, tissue repair and microbiota = other things we have to deal with
Describe immune system dynamics - overlap
Many events happening in parallel
Not linear story
Overlap over time
Can change locations and influence each other
Describe immune system dynamics = Specific stages and steps
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
What is titer
Virus titer = amount of virus
What are T cells
Types of lymphocytes
Where do T cells arise
In thymus from bone marrow progenitors
What requires the activation of T cells
Most adaptive immune responses = basically all of them
What can t cells recognize
Only recognize peptide fragments of antigen bound to self molecules of the major histocompatibility complex
Where are peptide mhc complexes expressed
On plasma membrane of apcs
Describe order of t cell activation
Tcr signallig - peptide on mhc
Costimulatory interaction
Cytokine signalling
What do lymphocytes carry
Different sets carry diff clusters of differentiation co receptors on their surface (cd)
Describe cd8+ T cells
Become effector cytotoxic t lymphocytes = CTLs
Describe cd4+ t helper cells
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
What do cd8+ T cells recognize
Antigen on mhc I
What do cd4+ T cells recognize
Antigen on mhc II
What does pamp do - link
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
