Lecture 9 Quiz: Regulation of T Cell Responses.

Question 1

T cells are capable of instant immune attack when they are:

Answer 1

Effector T cells
….
effector T cells are capable of performing their cytotoxic, helper or regulatory functions without requiring co-stimulation.

Question 2

Which is the major difference between CD8+ and NK cell cytotoxicity?

a.
Only natural killer cells induce target cell death by apoptosis.
b.
Cytotoxic T cells only kill host cells infected with intracellular bacteria.
c.
NK cells only use perforins and granzymes to induce cytotoxicity.

d.Cytotoxic T cells recognize virus-infected cells by recognizing viral antigens on the surface of the target cell.

Answer 2

Cytotoxic T cells recognize virus-infected cells by recognizing viral antigens on the surface of the target cell.
…

C is Incorrect, these components are also the key inducers of CTC mediated cytotoxicity.

Question 3

Granzymes induce apoptosis by which of the following downstream effector pathways?

a.	 Activation of caspase 8 and subsequently downstream effector caspases such as caspase -3 and -10.

b.	 Bid

c.	 Mitochondrial cell death pathway

d.	 All of the above options are correct

Answer 3

d.
All of the above options are correct
Answer Feedback:
This statement is true, granzymes can induce activation of these caspases directly or via activation of caspase 8. There are other correct responses.

Perforin pores cause osmotic lysis of target cell and allow granzymes to enter the target cell and induce apoptosis through various downstream effector pathways, including effector caspases, Bid and the mitochondrial cell-death pathway.

Question 4

T helper cells:

a.	 Express CD8+ on their surface.

b.	 Control the expansion and differentiation of T cells and B cells.

c.	 Are the main inducers of controlled cell death of virally infected host cells.

d.	 Cannot activate innate immune cells.

Answer 4

Control the expansion and differentiation of T cells and B cells.

…
C Incorrect, this statement best describes the effector function of cytotoxic T cells.

Question 5

Which of the following cytokines are mainly secreted by CD4 T helper 2 cells?

a.	 IL-2, IL-3 and TNF-alpha.

b.	 IL-6, TGF-beta and IL-17.

c.	 IL-4, IL-5 and IL-13

d.	 All of the above

Answer 5

c.

IL-4, IL-5 and IL-13

Question 6

As a mechanism of attack against extracellular bacteria and fungi, Th17 cells mediate the recruitment and stimulation of which type of innate immune cell?

a. 
Natural Killer cells.
b. 
Eosinophils
c. 
Basophils
 Correctd. 
Neutrophils

Answer 6

d.
Neutrophils
…
A is Incorrect, these cells attack virally infected cells and tumour cells.

Question 7

The major role of helping B cells to produce antibodies of high affinity by the dual ability of secreting either Th1 or Th2 cytokines is characteristic of which type of T cell

a. 
TFH cells.
b. 
TH1 cells.
c. 
T-reg cells
d. 
TH2 cells

Answer 7

.
TFH cells.
…
B is Incorrect, TH1 cells cannot produce TH2 cytokines. The major roles of TH1 cells are to activate infected macrophages and provide help to B cells for antibody production specific against extracellular bacteria.

Question 8

Which of the statements below correctly describe the function of CTLA-4?

a.	 Is a structural analogue of co-stimulatory molecules B7.

b.	 Is a receptor expressed on the surface of activated T cells that binds B7 with 20x more avidity than CD28.

c.	 Is a receptor expressed on the surface of antigen presenting cells that binds B7 with 20x more avidity than CD28.

d.	 Association with its ligand enhances T cell activation.

Answer 8

Is a receptor expressed on the surface of activated T cells that binds B7 with 20x more avidity than CD28.

…

A is Incorrect, CTLA-4 is a structural analogue of CD28.

Question 9

The biological action(s) of the cytokine IL-2 include:

a.	 Mediation of T cell expansion and differentiation into effector and memory cells

b.	 Inhibition of T-reg development and survival

c.	 Mediation of NK cell proliferation and enhancement of their cytotoxic function.

d.	 Options a and c are correct

Answer 9

a.
Mediation of T cell expansion and differentiation into effector and memory cells
c.
Mediation of NK cell proliferation and enhancement of their cytotoxic function.
Correctd.
Options a and c are correct

Question 10

A proposed mechanism of suppression by which T-reg may cause T cell metabolic disruption is:

a.	 CD25 mediated target cell-deprivation of cytokines causing apoptosis

b.	 Inhibition of target cell maturation by binding of LAG3 to MHCII.

c.	 Release of granzyme A or B by the T-reg which induces apoptosis of target T cells.

d.	 All of the above options are correct

Answer 10

a.
CD25 mediated target cell-deprivation of cytokines causing apoptosis
…

D is Incorrect, only option a describes suppression by metabolic disruption.