Immunology 5- types of T cells

Question 1

Dendritic cells also have co-stimulatory molecules (activated from pro-inflammatory mediators) on their surface. True or false?

Answer 1

True.

Question 2

Which class of MHC molecules do CD4 +T cells bind to?

Answer 2

MHC II.

Question 3

What do opsonin receptors do?

Answer 3

Opsonin receptors trap opsonised antigens in the b cell zone of lymph node. Makes it easier for B cell to bind to it.

Question 4

Which class of MHC molecules do CD8 +T cells bind to?

Answer 4

MHC I.

Question 5

Dendritic cells only show MHC complexes to CD8+ T cells. True or false?

Answer 5

False- present to CD4+ T cells and CD8+ T cells

Question 6

What are the two signals from dendritic cells?

Answer 6

First signal from the dendritic cell is the peptide antigen.

Second is from the co-stimulatory molecules

Question 7

What do the signals from dendritic cells do?

Answer 7

cause T Cells to activate and then differentiate and proliferate

Question 8

What do CD4+ T cells do?

Answer 8

• Mediate immune responses

- Will activate and grow into bigger CD4 + TH0 cells if bind to both signals from dendritic cells.

Question 9

What do CD4 + TH0 cells differentiate into?

Answer 9

CD4+ effector Th cells 
examples :
Th1 cells
Th2 cells
Tfh cells
Regulatory T cells

Question 10

What is IL-2 and its function?

Answer 10

A growth factor produced by CD4+ T cells. The activated CD4+ T cell can also start to express a receptor for IL-2 meaning it can be proliferated itself. This then allows lots of CD4+ Th0 cells to proliferate and produce more IL-2. IL-2 can then promote CD8+ T cells to proliferate and differentiate into CTLs.

Question 11

What molecules dictate what CD4+ TH0 cells differentiate into?

Answer 11

Cytokines in the lymph node.

Question 12

What do Th1 effector cells do?

Answer 12

• Migrate out of lymph nodes and enter infected/ inflamed tissues (undergo transendothelial migration)
• Help macrophages kill pathogens and become super killers
• Macrophages once they have phagocytosed, becomes activated and starts to release inflammatory cytokines which allow the Th1 cells to move into tissue
• macrophages also show MHC II peptide complex, if its specific to the Th1 cell, they will bind and then help secrete pro-inflammatory signals and co-stimulation

Question 13

Which type of T cell can produce IL-2?

Answer 13

CD4+ T cells

Question 14

What do Tfh cells do?

Answer 14

Help B cells in germinal centre reaction.

Question 15

How do Th1 cells make macrophages better killers?

Answer 15

Switch on expression of the NADPH oxidase genes.

Producing the toxic reactive oxygen species (like neutrophils)

Question 16

Pathogens can evade phagolysosomal killing by macrophages. True or false?

Answer 16

True- can escape from phagosome then grow in macrophage, killing it and then infecting other macrophages

Question 17

What do CD8+ T cells differentiate into?

Answer 17

killer Cytotoxic T lymphocytes (CTLs or Tc cells)

Question 18

How do CTLs kill infected host cells?

Answer 18

Migrate out of the lymph node and enter sites of infection in order to bind and kill infected host cells

CTL takes samples of the peptides from the cell, and it can recognise if it is a self or non-self peptide. (infected cell expressing MHC I and a viral peptide)

Question 19

How do infected host cells try to hide from CTLs?

Answer 19

Some infected cells that are dying from apoptosis send out signals, meaning other infected cells try to hide from the CTL by masking their MHC I complex, however NK cells kill anything that doesn’t have MHC I thus dying anyway.

Question 20

What is apoptosis?

Answer 20

Programmed cell death caused by CTLs.

CTLs contain granules which has toxic contents (proteins) to cause cell death.