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23 Cards in this Set
- Front
- Back
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What five things will activate a T-cells?
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1. MHC/peptide + co-stimulatory signal
2. Mitogens 3. Superantigens 4. Antibodies (in lab) 5. Chemical Mediators (in lab) |
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Normally, what signals are needed for T-cell activation (proliferation)? x 2
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Two competence signals
One progression signal |
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What are the two competence signals and give most common example of each.
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SIGNAL 1: TCR engagement (TCR binds to MCH + peptide)
SIGNAL 2: Co-stimulatory signal (CD28 binds to B7 on APC) |
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Give the most common progression signal.
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IL-2 and IL-2 Receptor
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What is the function of Competence signals?
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To tranduce a signal to the nucleus such that the gene responsible for the progression signal is transcribed.
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Define Anergy.
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When a T-cell CANNOT respond even if exposed to signal 1 and 2.
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What needs to happen for a T-cell to become anergic?
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The MHC and TCR bind, but the co-stimulatory DOES NOT!
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What does anergy build up?
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Tolerance
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CD8 T-cells become what?
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Cytotoxic (killer) cells
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CD4 T-cells become what?
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Helper cells (Th1 and Th2)
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Cell mediated immunity predominantly involves what type of T cell?
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Th1 cells
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Humoral immunity predominantly involves what type of T cell?
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Th2 cells
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What is Type IV Hypersensitivity or Tdth (T delayed type hypersensitivity)?
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Upon first contact with antigen, a CD4 helper T cell is activated, expresses all three signals, and proliferates.
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T/F - A naive CD4 T cell's future as a Th1 or Th2 is predetermined.
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False
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How does a CD4 Naive T-cell become a Th1 cell?
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Dendritic cells activate NK cells to secrete IL-12 and IFN-gamma which induces the naive cell to become Th1 cell.
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How does a CD4 Naive T-cell become a Th2 cell?
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Dendritic cells induce NK cells to secrete IL-4 which induces the naive cell to become Th2 cell.
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What Th1 secretion inhibits Th2 proliferation?
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IFN-gamma
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What Th2 secretion inhibits Th1 proliferation?
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TGF-beta and IL-10
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What is an effective Th1 cell and what is it's function?
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An effective Th1 cell is an activated cell that secretes cytokines to activate macrophages.
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What is the function of Th2 cells?
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Same as Th1, but also activate B cells to produce antibodies.
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During the CD8 Sensitization (Induction) phase, what are three ways that CD8 cells obtain activating signals?
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1. From dendritic cells, high levels of B7 can activate CD8 T cells, which will make IL-2, driving its own proliferation.
2. From APC, it will stimulate CD4 T cells, which will return the favor by activating the APC to stimulate CD8 activation. 3. CD 8 cells will provide their own signal 2. |
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In the absence of CD4, can CD8 become activated? If so, what happens?
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YES - but no memory cells, only response.
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What are the two proteins found in CD8 T cells, and what are their actions?
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Perforin - forms a pore
Granzymes - activate apoptosis |
