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23 Cards in this Set

  • Front
  • Back
What five things will activate a T-cells?
1. MHC/peptide + co-stimulatory signal
2. Mitogens
3. Superantigens
4. Antibodies (in lab)
5. Chemical Mediators (in lab)
Normally, what signals are needed for T-cell activation (proliferation)? x 2
Two competence signals

One progression signal
What are the two competence signals and give most common example of each.
SIGNAL 1: TCR engagement (TCR binds to MCH + peptide)

SIGNAL 2: Co-stimulatory signal
(CD28 binds to B7 on APC)
Give the most common progression signal.
IL-2 and IL-2 Receptor
What is the function of Competence signals?
To tranduce a signal to the nucleus such that the gene responsible for the progression signal is transcribed.
Define Anergy.
When a T-cell CANNOT respond even if exposed to signal 1 and 2.
What needs to happen for a T-cell to become anergic?
The MHC and TCR bind, but the co-stimulatory DOES NOT!
What does anergy build up?
CD8 T-cells become what?
Cytotoxic (killer) cells
CD4 T-cells become what?
Helper cells (Th1 and Th2)
Cell mediated immunity predominantly involves what type of T cell?
Th1 cells
Humoral immunity predominantly involves what type of T cell?
Th2 cells
What is Type IV Hypersensitivity or Tdth (T delayed type hypersensitivity)?
Upon first contact with antigen, a CD4 helper T cell is activated, expresses all three signals, and proliferates.
T/F - A naive CD4 T cell's future as a Th1 or Th2 is predetermined.
How does a CD4 Naive T-cell become a Th1 cell?
Dendritic cells activate NK cells to secrete IL-12 and IFN-gamma which induces the naive cell to become Th1 cell.
How does a CD4 Naive T-cell become a Th2 cell?
Dendritic cells induce NK cells to secrete IL-4 which induces the naive cell to become Th2 cell.
What Th1 secretion inhibits Th2 proliferation?
What Th2 secretion inhibits Th1 proliferation?
TGF-beta and IL-10
What is an effective Th1 cell and what is it's function?
An effective Th1 cell is an activated cell that secretes cytokines to activate macrophages.
What is the function of Th2 cells?
Same as Th1, but also activate B cells to produce antibodies.
During the CD8 Sensitization (Induction) phase, what are three ways that CD8 cells obtain activating signals?
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.
In the absence of CD4, can CD8 become activated? If so, what happens?
YES - but no memory cells, only response.
What are the two proteins found in CD8 T cells, and what are their actions?
Perforin - forms a pore

Granzymes - activate apoptosis