T cell Mediated Immunity Flashcards
Quiz 4
What are the three main secondary lymphoid organs
-lymph nodes
-spleen
-peyer’s patch
What is the difference between normal venules and high endothelial venules (HEV)
-thick with lots of cell-to-cell junction to allow lymphocyte movement
What is the role of chemokines
attract dendritic cells, then lymphocytes
Explains what happens when a T cell is activated and becomes ‘trapped’
-when activated, stays in lymph node
-proliferates
-once sufficient quantities, leave to do their job
What is the role of selectins
-aid in rolling and homing to lymphoid tissue
Why is it important for T cells to leave the lymph node if not activated?
want to survey ALL lymph node, leaving allows T-cells to travel to new/other lymph nodes
What drives naive T cells leaving
-signaling molecule S1P
What is the role of S1P
-naive T cells express a receptor for S1P (S1PR1) if not activated, move towards high S1P (leave)
-activated T cells repress S1PR1 (trap and proliferate)
-once proliferated, re-express S1PR1 (now the cell can leave
What are the three main APC’s
-macrophage/ Bcells (after activation) usually present antigen to CD4 Th cells
-Dendritic cells (making effector T cells: activation) present antigen to naive T cells and drive clonal expansion
What is priming
activation and differentiation of T cells
What happens when T cells are primed
-take naive T cells and turn them into effector T cells
-T cell interaction with MHC’s are different before/after priming
What is the first priming step
-APC interaction
-T cells initially bind APCs through low-affinity LFA-1:ICAM-1 interaction
Once forming a stable interaction, what are the three signals APC delivers
-TCR activation
-Co-stimulatory activation
-multiple activating cytokines
What is one inhibitory pathway exist to block improper T cell activation
-CTLA-4 binds B7
-prevents CD28 binding
-also activates an inhibitory signal pathway
What is IL-2
-play a key role in T cell differentiation
-turns up proliferation/ turns down apoptosis
-turns up cytotoxic T-cell activity
-recombinant IL-2 is used to treat some cancers
What determines the CD4+ T cell fate
-Fate-specifying cytokines
-most anti-inflammatory cytokines
How does TLR-induces IL-6 distinguish between Treg and Th17
-pathogens present (Make Th17 and activate neutrophils)
-Pathogens absent (Make Treg, suppress immune response, and important for tolerance)
Explain how CD4+ T cells cross-regulate
-most Th cells secrete cytokines that drive differentiation of themselves
How do effector T cells work
-collision
-antigen-specific binding
-immunological synapse formation
-release of cytokines and cytotoxins
What is effector cell binding to target dependent on
TCR recognizing their specific antigen:MHC
What is a peripheral (pSMAC) ring
LFA-1:ICAM-1
and is central circle (cSMAC)
signaling molecules
What components are apart of an immunological synapse
-supramolecule activation complex (SMAC)
-pSMAC
-cSMAC
What happens when Talin connects LFA-1 to the actin cytoskeleton
-right ‘simplified’ LFA-1 signaling
-LFA-1 binding to ICAM-1 leads to lots of signaling
-This leads to cytoskeletal remodeling
When does granule release happen
-granule release is polarized, happens at synapse
What is the benefit of granule release being polarized
-this greatly increases local concentration
-and it also prevents signaling with neighboring cells
What do all effector T cells release
cytokines
What is the Fas receptor
-what cell has and is know as the death receptor
-when bound (with TCR binding to antigen:MHC), induces apoptosis through a caspase cascade
