Exam II - Cell Mediated Immunity

Question 1

What are the specific cells of the CMI?

Answer 1

Antigen-specific T cells

Question 2

What are the nonspecific cells of the CMI?

Answer 2

NK cells, macrophages

Question 3

What peptide is linked to endogenous proteins to mark them for degradation?

Answer 3

ubuquitin

Question 4

In what structure are endogenous proteins degraded?

Answer 4

proteasomes

Question 5

What proteins assist in transport of peptides to the ER?

Answer 5

TAP

Question 6

Which receptors do TAP bind to in the ER?

Answer 6

the cleft of MHC Class I molecules

Question 7

Are CTLs fully differentiated when they exit the thymus?

What are they referred to as at this point in development?

Answer 7

No.

Pre-CTLs or Naive CD8⁺ T Cells

Question 8

What are the two signals required for activatoin of a CTL?

Answer 8

Recognition of MHC class I-associated peptides, and co-stimulators and/or cytokines

Question 9

What type of cells can provide the necessary 2nd signal for activation of a CTL?

Answer 9

APCs

Question 10

Are secondary signals needed to trigger the effector function of activated CTLs?

Answer 10

Yes

Question 11

What are the enzymes used by the CTL to kill a target cell?

Answer 11

Perforins and granzymes

Question 12

How does perforin interact with the membrane of a target cell?

Answer 12

Perforin is a pore-forming protein. When interacting with Ca ions, it polymerizes to form tubular pores call polyperforins

Question 13

How does the release of granzymes trigger apoptosis in target cells?

Answer 13

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.

Question 14

What is the role of the Fas ligand in triggering apoptosis in target cells?

Answer 14

It bing to the Fas protein and activates caspases, triggering cell apoptosis

Question 15

How is bystander lysis of neighboring cells prevented?

Answer 15

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)

Question 16

What are the properties of NK cells

Answer 16

They are large, granular lymphocytes that originate in bone marrow. They do NOT recirculate

Question 17

What is the main function of NK cells?

Answer 17

recognize and kill certain tumor cells and virus-infected cells. THey also secrete IFN-γ to activate macrophages

Question 18

Which cells are targeted by NK cells?

Answer 18

cells that fail to express, or express reduced, MHC class I proteins

Question 19

What does the KAR bind to?

What does this binding trigger?

Answer 19

CHO molecules on self-cells

NK cells to kill target cells

Question 20

What does the KIR bind to?

What is the function of this binding?

Answer 20

MHC Class I molecules

Inhibition of killing

Question 21

Which signal is dominant: KIR or KAR?

Answer 21

KIR

Question 22

How is the macrophage activated?

What functions do activated macrophages possess?

Answer 22

The macrophage is activated by CD40L-CD40 interactions, IFN-γ, and bacterial endotoxin

Synthesis of NO

Question 23

Which cells and cytokines control macrophage activation?

Answer 23

T_H1 and NK Cells, CD40L, CD40, IFN-γ

Question 24

What is the most important cell in cell mediated immunity?

Answer 24

Cytotoxic (CD8⁺) T Cells

Question 25

Name all the components of intrinsic apoptotic pathway

Answer 25

granzymes/perforins, caspase 9 –> apoptosis

Question 26

Name all the components of extrinsic apoptotic pathway

Answer 26

CD95L (Fas ligand) / CD95 –> caspase 8 –> apoptosis

Question 27

How do NK Cells kill the cells that don’t express MHC class I?

Answer 27

granzymes and perforins (just like CTLs)