CD8+ T cells

Question 1

What is the main function of CD8+ T cells?

Answer 1

To recognize and destroy infected or abnormal cells through antigen-specific cytotoxicity

Question 2

What molecules do CD8+ T cells recognize?

Answer 2

MHC Class I molecules presenting peptides from endogenous antigens

Question 3

How do CD8+ T cells avoid harming uninfected cells?

Answer 3

They specifically target only cells presenting antigens on MHC Class I and leave neighboring cells unharmed

Question 4

What is the role of the immunological synapse in CD8+ T cell function?

Answer 4

It is the interface between the CD8+ T cell and the target cell where granules are released to induce apoptosis

Question 5

What are the key effector molecules in CD8+ T cells?

Answer 5

Perforin granzymes and Fas ligand

Question 6

What is the role of perforin in CD8+ T cell killing?

Answer 6

Perforin forms pores in the target cell membrane to allow entry of granzymes

Question 7

What is the role of granzymes in CD8+ T cell killing?

Answer 7

Granzymes enter the target cell and activate caspases leading to apoptosis

Question 8

What is the role of Fas ligand on CD8+ T cells?

Answer 8

Fas ligand interacts with Fas receptors on target cells to trigger the extrinsic apoptosis pathway

Question 9

What are the two pathways of apoptosis triggered by CD8+ T cells?

Answer 9

The intrinsic mitochondrial pathway and the extrinsic Fas-dependent pathway

Question 10

How is the intrinsic pathway of apoptosis activated?

Answer 10

CD8+ T cells release granzymes that activate pro-apoptotic proteins leading to cytochrome c release from mitochondria

Question 11

How is the extrinsic pathway of apoptosis activated?

Answer 11

Fas ligand on CD8+ T cells binds to Fas receptors on target cells activating pro-caspase 8

Question 12

What happens after cytochrome c is released from mitochondria during apoptosis?

Answer 12

Cytochrome c activates apoptotic protease activating factor 1 Apaf-1 and caspase-9 leading to cell death

Question 13

What are the key features of CD8+ T cell-mediated killing?

Answer 13

Antigen specificity rapid apoptosis induction and the ability to target multiple infected cells sequentially

Question 14

What are gd T cells?

Answer 14

A subset of T cells with limited TCR diversity that recognize non-peptide antigens without MHC restriction

Question 15

Where are gd T cells mainly found?

Answer 15

In epithelial tissues as intraepithelial lymphocytes

Question 16

What are invariant NKT iNKT cells?

Answer 16

A type of innate-like lymphocyte that recognizes glycolipid antigens presented by CD1d molecules

Question 17

What are MAIT cells?

Answer 17

Mucosal-associated invariant T cells that respond to bacterially derived folate metabolites presented by MR1 molecules

Question 18

What is the significance of MAIT cells in immunity?

Answer 18

They are abundant in mucosal tissues like the gut and liver and play a role in the mucosal immune system

Question 19

How do iNKT cells differ from classical T cells?

Answer 19

They have limited TCR diversity and recognize microbial glycolipids rather than peptides

Question 20

What is the role of sentinel proteins like p53 in apoptosis?

Answer 20

They detect cellular stress and activate pro-apoptotic pathways in response to CD8+ T cell signals

Question 21

How do CD8+ T cells contribute to adaptive immunity?

Answer 21

By eliminating infected cells and preventing pathogen replication they reduce the antigen load for other immune responses

Question 22

What is the difference between perforin-dependent and Fas-dependent killing by CD8+ T cells?

Answer 22

Perforin-dependent killing involves granules while Fas-dependent killing relies on Fas-Fas ligand interactions