Ch. 8 Immune System Regulation Flashcards
(28 cards)
What do activated helper t cells secrete
TNF and IFN-y which activate the immune system
What do activated regulatory t cells secrete
TFGB and IL-10 which restrain the immune system
What 3 things does TFGB do
Transforming growth factor beta = binds to receptors on t cells, reduces proliferation, reduces CTL killing
What does IL-10 do
Binds to receptors on T cells, blocks co-stimulatory signals (CD28), reduces proliferation
What is significant about IL-10 blocking co-stimulatory signals (CD28)
More difficult to activate
What do epithelial cells of the intestines produce
TFGB
TFGB does what in the intestines
Cause T cells in peyer’s patches to become regulatory t cells
Regulatory t cells do what in intestines
Release cytokines that encourage calmer mucosal immune system
What helps to prevent allergies and what causes allergies
Mast cells prevent, allergies caused by mast cell degranulation
What do virgin T cells express for co-stimulation
CD28 receptors
What do activated APC’s make that binds to CD28 and what does that do
They make B7 that binds to CD28 providing the costimulation necessary for T cell activation
Very experienced T cells make more of what
CTLA-4
What does CTLA-4 do
Binds to B7 blocking CD28 reducing response, binds to B7 with affinity 1000 times higher than CD28, out competes CD28
What is B7
A costim. Molecule expressed on surface of APC’s
What is CD28
Receptor molecule on T cell, when activated it amplifies signal and lowers TCR number crosslinks needed for activation
What is CTLA-4
Receptor molecule on very experienced T cells, brought to membrane competing for B 7 making costim. Activation difficult
What are PD1 cells
Programmed death 1 receptor is expressed on activated T cells/others
Where is PD1-L expressed
On other WBC’s and inflamed tissues
What does engagement of PD1 by PD1-L do?
Slows proliferation and may induce apoptosis
Any cell expressing PD1 could by ____ by engaging with PD1-L
Down regulated
Any cell expressing PD1-L can turn down what
Immune response
Once activated what happens to T cell longevity
Greatly reduced by AICD
What is AICD
Activation induced cell death
What happens in AICD?
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
