Exam II - Cell Mediated Immunity Flashcards
What are the specific cells of the CMI?
Antigen-specific T cells
What are the nonspecific cells of the CMI?
NK cells, macrophages
What peptide is linked to endogenous proteins to mark them for degradation?
ubuquitin
In what structure are endogenous proteins degraded?
proteasomes
What proteins assist in transport of peptides to the ER?
TAP
Which receptors do TAP bind to in the ER?
the cleft of MHC Class I molecules
Are CTLs fully differentiated when they exit the thymus?
What are they referred to as at this point in development?
No.
Pre-CTLs or Naive CD8+ T Cells
What are the two signals required for activatoin of a CTL?
Recognition of MHC class I-associated peptides, and co-stimulators and/or cytokines
What type of cells can provide the necessary 2nd signal for activation of a CTL?
APCs
Are secondary signals needed to trigger the effector function of activated CTLs?
Yes
What are the enzymes used by the CTL to kill a target cell?
Perforins and granzymes
How does perforin interact with the membrane of a target cell?
Perforin is a pore-forming protein. When interacting with Ca ions, it polymerizes to form tubular pores call polyperforins
How does the release of granzymes trigger apoptosis in target cells?
They enter target cells mainly through the perforin-created membrane channels. They cleave and activate caspases to then cleave several substrates and induce target cell apoptosis.
What is the role of the Fas ligand in triggering apoptosis in target cells?
It bing to the Fas protein and activates caspases, triggering cell apoptosis
How is bystander lysis of neighboring cells prevented?
CTLs orient their secretory apparatus to focus it on the point of contact with the target cell (a highly polar release of the effector molecules)
What are the properties of NK cells
They are large, granular lymphocytes that originate in bone marrow. They do NOT recirculate
What is the main function of NK cells?
recognize and kill certain tumor cells and virus-infected cells. THey also secrete IFN-γ to activate macrophages
Which cells are targeted by NK cells?
cells that fail to express, or express reduced, MHC class I proteins
What does the KAR bind to?
What does this binding trigger?
CHO molecules on self-cells
NK cells to kill target cells
What does the KIR bind to?
What is the function of this binding?
MHC Class I molecules
Inhibition of killing
Which signal is dominant: KIR or KAR?
KIR
How is the macrophage activated?
What functions do activated macrophages possess?
The macrophage is activated by CD40L-CD40 interactions, IFN-γ, and bacterial endotoxin
Synthesis of NO
Which cells and cytokines control macrophage activation?
TH1 and NK Cells, CD40L, CD40, IFN-γ
What is the most important cell in cell mediated immunity?
Cytotoxic (CD8+) T Cells
Name all the components of intrinsic apoptotic pathway
granzymes/perforins, caspase 9 –> apoptosis
Name all the components of extrinsic apoptotic pathway
CD95L (Fas ligand) / CD95 –> caspase 8 –> apoptosis
How do NK Cells kill the cells that don’t express MHC class I?
granzymes and perforins (just like CTLs)
