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66 Cards in this Set

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What are the soluble effector molecules produced by CTL t-cells?
1. Cytotoxins (perforins and granzymes)

2. IFN-gamma

3. TNF-beta
What are the membrane-bound effector molecules produced by CTL t-cells?
Fas ligand (FASL)
What are the soluble effector molecules produced by Th1 t-cells?
1. IL-2

2. IL-3

3. TNF-beta

4. IFN-gamma

5. GM-CSF (high)
What are the membrane-bound effector molecules produced by Th1 t-cells?
Tumor necrosis factor beta (TNF-beta)
What are the soluble effector molecules produced by Th2 t-cells?
1. IL-3

2. IL-4

3. IL-5

4. IL-6

5. IL-10

6. IL-13

7. GM-CSF (low)
What are the membrane-bound effectors produced by Th2 effector T-cells?
CD40 ligand
What are CTLs aka?
Cytotoxic T-Lymphocytes
What are CTLs generated by?
CTLs are generated by immune activation of Tc cells.
What are the two phases of response that CTLs are involved in?
1. Tc cells undergo activation and differentiate into active CTLs.

2. Effector CTLs recognize Ag-class I MHC complexes.
List 4 properties of CTLs.
1. Lytic

2. Recognize and eliminate alter non-self cells

3. CD8+

4. MHC I restricted
What are CTL-Ps aka?
CTL Precursors. They are naive Tc cells that are not capable of killing.
The threshold to activate CTL-Ps to become CTLs is ? and requires ? signals.
The threshold to activate CTL-Ps to become CTLs is high and requires 3 signals.
List the 3 signals required to activate CTL-Ps.
1. An Ag-specific signal transmitted by TCR complex upon recognition of MHC I complexed to a "licensed" APC (usually a dendritic cell).

2. Costimulatory signal transmitted by CD28-B7

3. Signal induced by IL-2 binding to IL-2R resulting in proliferation and differentiation of the Ag-activated CTL-P into effector CTLs.
In the generation of effector CTLs what gives dendritic cells a "license"? What becomes expressed?
Th1 and costimulation with CD40-CD40L gives dendritic cells a "license". IL-2R becomes expressed.
The proliferation of memory CTL-Ps is not dependent upon what?
The proliferation of memory CTL-Ps is not dependent on Th cells.
The proliferation of memory CTL-Ps is not dependent upon Th cells and may also not require what else?
CD28-B7 interactions may also not be required.
Ag-activated memory CTL-Ps appear to secrete sufficient amounts of IL-2 to do what?
They secrete sufficient amounts of IL-2 to stimulate their own proliferation and differentiation into CTLs.
The increase in Ag-specific CD8+ cells is measurable. Describe how this can be observed in mice.
Mice were infected with VSV (vesicular stomatitis virus). The distribution of VSV-specific CD8+ cells is not uniform. There is a greater percentage in these organs in this order: kidney>lungs>liver.
The killing of target cells occurs in ?.
The killing of target cells occurs in stages.
What is the primary event in CTL-mediated killing?
The primary event in CTL-mediated killing is conjugate formation.
Conjugate formation is the primary event in CTL-mediated killing. Describe the process.
The process begins with TCR-CD3 on the CTL recognizing Ag-MHC I complex. The integrin receptor (LFA-1) on CTL binds to ICAMS on target cell forming the conjugate. Once complete the CTL cell goes back for recycling.
Pore formation (caused by ?)in target cell membranes mediates what?
Pore formation (caused by perforin) mediates granzyme entry into target cell.
What is Ca++ required for?
Exocytosis, insertion of perforin monomers into the membrane, and polymerization to form cylindrical pores.
Give a basic step by step breakdown of pore formation in target cells.
1. Increased Ca++

2. Granule fuses with plasma membrane of CTL

3. Opens and perforin monomers expel

4. Perforin assembly poymerizes

5. Pore forms and fluid rushes in

6. The cell burst (apoptosis)
CTL-stimulated target cell apoptosis occurs by how many pathways?
Two

1. Fas pathway

2. Perforin-Granzyme pathway
The Fas pathway involves the association of ? and ?.
It involves the assoc. of Fas and FADD

It is one of the pathways for CTL-stimulated target cell apoptosis.
Describe the Perforin-Granzyme Pathway that mediates CTL-stimulated target cell apoptosis?
1. Exocytosis releases both perforin and granzyme

2. Granzyme B enters target cell in two ways
(By perforin pores AND binding mannose-6-phosphate)
What kind of cytotoxicity do NK cells have?
Non-specific cytotoxicity
What percentage of circulating lymphocytes are NK cells?
5-10% of circulating lymphocytes are NK cells.
What do NK cells attack?
Attack viruses, other intracellular pathogens, and tumors.
What do NK cells produce to influence commitment?
NK cells produce INF-gamma to influence T-cell subtype commitment.
NK cell activity is stimulated by what?
INF-alpha, INF-beta, and IL-12
NK cells are the ? against ? infections.
NK cells are the 1st line of defense against viral infections.
The presence of INF-gamma, INF-alpha, and INF-beta indicate what?
They indicate the presence of viral infected cells. They are released by viral infected cells.
Once INF-alpha,gamma, and beta are released by virus infected cells what happens to the NK cell pop?
It increases
Once INF-alpha, gamma, and beta are released and the NK cell pop increases what do CTLs do?
CTLs take over and produce memory cells for that virus.
The presence of what drops as the presence of virus titer increases?
The presence of IFN-alpha, beta, and gamma as well as the presence of NK cells drop as the virus titer increases. (see slide on pg 6)
What do NK cells and T-cells share?
They share a common early progenitor cell.
NK cells do not develop where?
Do not develop in the thymus.
NK cells do not undergo ? ?.
They do not undergo gene rearrangement. Because they do not have Ag specificity. (they don't care what they 'kill')
What do RAG-1 KO mice lack? What are they used to study?
They lack adaptive immunity (so no T and B cells). They are used to study immune system rxns to different Ags.
What will keep RAG-1 KO mice healthy?
NK cells and intact innate immunity mxms will keep them healthy enough if housed in clean conditions. (Because they lack adaptive immunity, T and B cells)
Do NK cells or CTL cells have FasL? For what?
NK cells have FasL on their surface and can induce death (apoptosis) in Fas-bearing targets.
What do NK cell granules contain?
Perforin and granzymes
Which cells have memory NK or CTLs?
CTLs (NK has no memory)
Which cells are not MHC restricted, NK cells or CTLs?
NK cells are not MHC-restricted.
Which cells do not express Ag-specific receptors, CTLs or NK cells?
Nk cells do not express Ag-specific receptors.
Which cells require activation, NK cells or CTL cells?
CTLs require activation (and NK cells do not)
NK cells do not req activation because they are always ? with large ? ?.
They are always cytotoxic with large cytoplasmic granules.
What does the 'Opposing Signals Model' state?
Activation and inhibition receptors are found. This is involved in the ability of the NK cells to distinguish between healthy cells from infected or cancerous cells is balanced.
How can NK activating signals be delivered?
Delivered by cytokines:

INF-alpha, beta, and gamma

IL-12

IL-15
NK cells have activation and inhibition receptors. Which are better characterized?
Inhibitory receptors are better characterized.
Most of the inhibitory receptors found on NK cells are ? molecules.
Ig-like molecules
What are the intracellular sequences involved with the inhibitory receptors of NK cells?
ITIMs (not ITAMs) (immunoreceptor tyrosine phosphate inhibitory motifs)
How do the inhibitory receptors of NK cells block the lysis of target cells by NK cells?
1. Detect normal levels of MHC-I expression on potential target cells.

2. Also prevent NK cell proliferation and induction of cytokines like INF-gamma and INF-alpha.
The opposing signals model of NK cells states that the engagement of inhibitory NK cell receptors by ? delivers and ? signal that counteracts the ? signal.
The opposing signals model of NK cells states that the engagement of inhibitory NK cell receptors by MHC-I delivers and INHIBITORY signal that counteracts the STIMULATORY signal.
List two NK cell inhibitory receptors?
KIRs and CD94/NKG2
If an NK cell comes into contact with a normal cell what happens to the inh and activating receptors?
If MHC-I seems normal then the activating receptor does not activate and their is no killing.
If an NK cell comes into contact with a virus-infected cell what happens to the inh and activating receptors?
The inhibitory cell detects an abnormal level. There is then no counteropposition signal to the activating receptor and the cell is then free to kill.
What cells are a recent discovery?
NKT cells
What cells do NKT cells have properties in common with?
CTL and NK cells (hybrid)
NKT cells have ? complexes but shares little else with the others.
They have TCR complexes but share little else with the others. TCR does not recognize MHC-bound peptides and this is an exception to the norm for TCRs. It recognizes a glycolipid.
NKT cells are part of the ? ? system.
NKT cells are part of the innate immune system.
NKT cells may play a part of ? immunity.
NKT cells may play a part of antibacterial immunity.
NKT cells have no ?.
NKT cells have no memory.
Where do NKT cells develop?
They develop in the thymus. This is why they have TCRs.