Ch. 8 Immune System Regulation

Question 1

What do activated helper t cells secrete

Answer 1

TNF and IFN-y which activate the immune system

Question 2

What do activated regulatory t cells secrete

Answer 2

TFGB and IL-10 which restrain the immune system

Question 3

What 3 things does TFGB do

Answer 3

Transforming growth factor beta = binds to receptors on t cells, reduces proliferation, reduces CTL killing

Question 4

What does IL-10 do

Answer 4

Binds to receptors on T cells, blocks co-stimulatory signals (CD28), reduces proliferation

Question 5

What is significant about IL-10 blocking co-stimulatory signals (CD28)

Answer 5

More difficult to activate

Question 6

What do epithelial cells of the intestines produce

Answer 6

TFGB

Question 7

TFGB does what in the intestines

Answer 7

Cause T cells in peyer’s patches to become regulatory t cells

Question 8

Regulatory t cells do what in intestines

Answer 8

Release cytokines that encourage calmer mucosal immune system

Question 9

What helps to prevent allergies and what causes allergies

Answer 9

Mast cells prevent, allergies caused by mast cell degranulation

Question 10

What do virgin T cells express for co-stimulation

Answer 10

CD28 receptors

Question 11

What do activated APC’s make that binds to CD28 and what does that do

Answer 11

They make B7 that binds to CD28 providing the costimulation necessary for T cell activation

Question 12

Very experienced T cells make more of what

Answer 12

CTLA-4

Question 13

What does CTLA-4 do

Answer 13

Binds to B7 blocking CD28 reducing response, binds to B7 with affinity 1000 times higher than CD28, out competes CD28

Question 14

What is B7

Answer 14

A costim. Molecule expressed on surface of APC’s

Question 15

What is CD28

Answer 15

Receptor molecule on T cell, when activated it amplifies signal and lowers TCR number crosslinks needed for activation

Question 16

What is CTLA-4

Answer 16

Receptor molecule on very experienced T cells, brought to membrane competing for B 7 making costim. Activation difficult

Question 17

What are PD1 cells

Answer 17

Programmed death 1 receptor is expressed on activated T cells/others

Question 18

Where is PD1-L expressed

Answer 18

On other WBC’s and inflamed tissues

Question 19

What does engagement of PD1 by PD1-L do?

Answer 19

Slows proliferation and may induce apoptosis

Question 20

Any cell expressing PD1 could by ____ by engaging with PD1-L

Answer 20

Down regulated

Question 21

Any cell expressing PD1-L can turn down what

Answer 21

Immune response

Question 22

Once activated what happens to T cell longevity

Answer 22

Greatly reduced by AICD

Question 23

What is AICD

Answer 23

Activation induced cell death

Question 24

What happens in AICD?

Answer 24

Fas receptor protein is a death receptor on cells. So Fas/FasL on same cell can engage (suicide) or Fas on T cell engages FasL on other T cells causing apoptosis (homocide). experienced T cells more sensitive than virgin

Question 25

Where are CTLA-4 regulators stored

Answer 25

Inside naive T cells

Question 26

What presents more Fas protein

Answer 26

Experienced T cells, virgin do not express much

Question 27

Repeated activation on T cells causes what

Answer 27

Much more Fas protein on the T cells

Question 28

What are the lifespans of immune cells

Answer 28

Neutrophil = die after few days, NK cells = 1-2 weeks, macrophages = months, dendritic cells = live for week after reaching lymph node, plasma b cells= die 5 days after making 2,000 antibodies/second, antibodies = longest lived (IgG) half life of 3 weeks