Lecture 11

Question 1

What transcription factor regulates transcription of genes encoding for perforin, granzyme, and interferon gamma?

Answer 1

T-bet

Question 2

What is the role of helper T cells in the differentiation of CTLs?

Answer 2

CD4+ cells produce cytokines that stimulate CTL differentiation, and enhance ability of APCs to stimulate CTL differentiation

Question 3

APC Licensing

Answer 3

CD4+ T cell recognizes Ag on MHC class II and delivers activating signals through CD80/86 and CD40; activated CD4+ expresses CD40L - the CD40/CD40L interaction upregulates CD80/CD86 on APCs and increases efficiency of CD8+ T cell differentiation

Question 4

What is the role of IL-2 in CTL activation?

Answer 4

Promotes proliferation, differentiation of CD8+ T cells into CTLs, memory cells; activation leads to increase in IL-2R

Question 5

What is the role of IL-12 in CTL activation?

Answer 5

Stimulate differentiation of naive CD8+ T cells into effector CTLs. Required for survival, development of optimal effector functions

Question 6

What is the role of IL-15 in CTL activation?

Answer 6

Important for survival of memory CD8+ T cells

Question 7

What is the role of IL-21 in CTL activation?

Answer 7

Produced by activated CD4+ T cells and play a role in induction of CD8+ T cell memory and prevention of CD8+ T cell exhaustion

Question 8

Exhaustion of CD8+ T cells

Answer 8

Active suppression of immune responses (usually pertains to a chronic viral infection); show reduced IFN-gamma production, increased expression of PD-1 inhibitory receptor

Question 9

Immunologic synapse

Answer 9

Formed by close contact between CTL/target cell after recognition of Ag; prevents bystander cells from being injured during CTL killing of target cell

Question 10

Granzyme mediated apoptosis

Answer 10

Perforin perturbs membrane, allows for insertion of granzyme and perforin; granzyme B activates caspase 3 which triggers apoptosis

Question 11

Fas-FasL mediated apoptosis

Answer 11

FasL binds to Fas, activating caspase 8; pathway to apoptosis via Type I or Type II cells

Question 12

Type I cells/thymocytes in Fas-FasL mediated apoptosis

Answer 12

Caspase-8 directly cleaves caspase-3; activates CAD and causes DNA degradation

Question 13

Type II cells in Fas-FasL mediated apoptosis

Answer 13

Caspase-8 cleaves Bid, releasing cytochrome c; cytochrome c, Apaf-1, ATP activate caspase-9 which activates caspase-3; caspase-3 activates CAD and causes DNA degradation