2.2.7 T-cell mediated immunity Flashcards
The _____ cell is the most important in primary response
dendritic
when T-cells leave the thymus what are they considered?
mature Naive
______ have encountered antigen and are ready to act
Effector T-cells
Which Effector T-cell deals with pathogens in the cytosol, and recognizes MHC1?
Cytotoxic CD8
Which Effector T-cell deals with pathogens in macrophage vesicles, and recognizes MHC2
CD4 / THC1
what is the effector activation of CD8? CD4?
CD8: apoptosis
CD4: cytokines
can an alpha/beta t-cell bind without a MHC?
no!
Class 1 molecules (HLA-A,B,C) are found on what cells?
all nucleated EXCEPT RBC!!
where are class II molecules found?
APCs
APCs express what MHC?
MHC1 and MHC2
_____ are immature dendritic cells. What can they do and not do?
Langerhan’s cells
They CAN process, they CANT present antigens
When a Langerhan cell reaches the lymph node it can transform to a ______ which can _____
mature dendrite, can present but NOT process
Where do mature/naive cells travel/interact with antigen?
mature/naive cells leave thymus –> enter lymph node –> encounter antigen on dendrite
what are the 2 ways naive T-cells can enter the lymph node?
- High endothelial venules (HEV)
- Lymphatics
How do T-cells interact with endothelium cells in the blood?
via adhesion molecules
where are adhesion molecules expressed? what are they called?
on both T-cells and endothelium cells
- LFA-1 on T-cell, ICA-1 on endothelium
what happens once LFA-1 and ICAM-1 interact?
diapedesis, lymphocyte can enter lymph node
If a TCR does recognize an antigen, there is a conformational change that causes what to happen?
LFA-1 to bind tighter to ICAM-1, prolongs cell-cell contact
what are the 2 signals involved in the activation of T-cells?
- MHC and TCR co-receptors
- co-stimulators (B7 on APC, CD28 on T-cell)
Costimulatory signal + specific signal = _____
Specific signal alone = _____
Costimulatory signal alone = ______
- Activated T-cell
- Anergic T-cell
- No effect
If T-cell recognized self antigen, it would become what?
anergic
once a T-cell becomes anergic can it ever revert back to normal?
NO
If T-cell cant find the appropriate antigen in the Thymus, it does what?
leaves by efferent vessel
Naive T-cells that encounter their antigen will become _____
effector T-cells or memory t-cells
what is the role of IL-2 in T-cell activation?
- activated T-cells express high affinity IL-2 receptor (with gamma, beta and alpha)
- Activated T-cell secretes IL-2
- IL2 binds to IL2 receptor and sends a signal to T-cell
- this induces proliferation
completed IL2 receptor with gamma, beta, and alpha is called what?
CD25
cytokines can have what kinds of effects?
autocrine, paracrine, endocrine
what kinds of effects can interleukins have?
Redundant (different ILs have same effect)
Synergic
Antagonistic
What different subsets do CD4 T-cells have?
TH1, TH2
what does CD4-TH1 play a role in?
cell mediated immune response
what does CD4-TH2 play a role in?
providing cytokines to activate B-cells
what types of cytokines are present in TH1?
IL2, gamma interferon
what types of cytokines are present in TH1?
IL2, IFN-gamma
what types of cytokines are present in TH2?
IL4, IL5, IL6, IL10, IL13
TH1 interferons are inhibited by _____
TH2 interferons (IL4, IL10)
TH2 interferons are inhibited by _____
TH1 interferons (IL12, gamma IF)
TH1 responds to _____ pathogens while TH2 responds to _____ pathogens
1- Intracellular
2- Extracellular
TGF-B results in what kind of cell?
T- regulatory cell that expresses FoxP3
the 4th kind of T-cell is _____
Th17
what are the 5 kinds of T-cells we need to know?
TH1, TH2, TFH, TH17, Treg
TH2 and TFH cells both have which cytokine in common?
IL4
what is the major difference between TH2 and THF cells?
- TH2 cells leave the lymph node as an effector cell
-TFH cells go to B cell area
How does TH1 cell work?
- TH1 cell + MHC II on macrophage
- T-cell activates macrophage
- t-cell releases gamma interferon, this further activates macrophage to kill intracellular bacteria
how are tuberculoid and lepromatous leprosy different?
Tuberculoid:
- LOW infectivity
-granulomas and local inflammation
normal t-cell responsiveness
Lepromatous:
- HIGH infectivity
-disseminated infection, bone, cartilage, nerve damage
- Hypergammaglobulinemia
which 2 are the pro-inflammatory cytokines?
IFN-alpha, IL-2
along with IL6,IL8,IL12, IL17, IL1
______ is known as a chemokine
IL8
_____ may play a role in bone resorption
IL1
Dendritic cells can activate naive CD8 cells via _______ as co-stimulatory signal
B7-CD28
After Cd28 and B7 bind, activated CD8+ T-cells can produce ______
IL2s
stimulation of naive CD8 T-cells by APC can result in ______
proliferation of cells and subsequent effector cells
what is missing on CD8 effector cells?
B7 and CD28. No co-stimulatory factors are required
what are the effector cells that CD8 T-cells secrete to cause apoptosis?
Perforin, Granzymes, and granulysin
_______ is a protein CD8 uses to form a pore in the target membrane
Perforin
how is perforin different from MAC?
causes a pore but doesn’t cause cell lysis, pore allows proteins in (ex: granzyme)
____ are serine proteases that CD8 use to drive a target cell into apoptosis
Granzyme
Why not lyse a cell that is intracellularly infected?
if we lyse it, the bacteria would escape, we dont want that
_____ cells also use Perforin and release granozymes. The difference is that this cell has a non-specific function
NK
once the CD8+ T-cell destroys a target, can it kill another cell?
Yes! it can regenerate granules and kill more cells
Summary: what cytokines do TH1, TH2, TFH, TH17 and Treg produce?
TH1: IFN-gamma, IL2
TH2: IL4, IL-10, IL-13, IL-6
TFH: IL4, IL6
TH17: IL-17
Treg: TGF-B, IL-10
