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PA2203- Mod 6 > Regulation of Immune Response > Flashcards

Regulation of Immune Response Flashcards

1
Q

What is immune tolerance + 3 things its important for

A

A state of immune non responsiveness towards an antigen

  1. Avoiding rxns to self antigens
  2. minimizing tissue damage
  3. minimizing immune rxns
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2
Q

Where does t cell negative selection take place

A

occurs in the thymus to self antigens loaded on MHC

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3
Q

what are the 3 outcomes of t cell negative selection

A

weak binding- thymocyte survives

moderate binding- t cell may undergo apoptosis/ transform into nTreg cells

Strong binding- apoptosis

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4
Q

Where does b cell negative selection take place

A

Takes place in bone marrow, does not require MHC

rxn with self antigens

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5
Q

What are the 3 outcomes of b cell negative selection

A

no self rxn- migrate to periphery

multivalent self- cross linked to 2 b cell receptors- clonal deletion or receptor editing

Non cross linking (low affinity)- migrates to periphery as anergic or clonally ignorant (can respond to other antigens but not self)

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6
Q

What is the main method of central immune tolerance

A

Negative selection of t or b cells

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7
Q

What is costim blockage

A

when a tell attempts to interact with a non activated APC the t cell doesn’t receive all necessary signals and may undergo apoptotic death/anergic etc)

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8
Q

When an APC is not activated what inhibitor costim can it express

A

CTLA-4

-inhibitory to t cells

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9
Q

How are Treg cells created

A

during neg selection T cells may bind with moderate activity to self antigens and may survive to become ntregs

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10
Q

What is the function of naturel T reg cells

A

Patrol body to find self epitope and if they do they exert regulatory functions to minimize response to self antigens in the periphery

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11
Q

What do induced T reg cells do + are specific for

A

made in peripheral lymphoid organs

  • typically specific for non self antigens and are important for control of inflammatory responses
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12
Q

What do t reg cells release and what do they do (2)

A
  1. Immunosuppressive cytokines (IL10, TGFB)

2. Cytotoxic molecules (perforin, granzyme)- to attack t cells that are attacking self

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13
Q

How does IL10 work and what does it attach to

A

Binds to IL 10 receptors on immune cells/tissues

  • impairs expression of pro inflammatory cytokine genes
  • down regulates MHC class II expression + co stim molecules
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14
Q

What can TGFb do

A

can impair th1, th2 and b cell activation

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15
Q

how are tolerogenic Dendritic cells made

A

Tregs induce dendritic cells to become tolerogenic

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16
Q

What are the differences with tolerogenic DCs (4)

A
  1. Display lower expression of costims
  2. Maturation resistance
  3. Inhibit activity of effector t cells in periphery
  4. secrete immunomodulatory molecules (IL10, IDO)
17
Q

What can Tregs do to ATP

A

has cell surface enzymes that hydrolyze extracellular ATP to free adenosine

-adenosine inhibits the effector functions of various immune cell pops

18
Q

what is an example of a myeloid derived suppressor cell

A

M2 macrophages

19
Q

What are the main targets of myeloid derived suppressor cells and what do they release (3)

A

t cells are main target

-immune suppression by releasing TGFb, IL10, IDO

20
Q

How are t cells killed off after completing immune response

A

Fas on activated t cells bind to FasL on activated CTLs (leads to death by apoptosis via caspases)

21
Q

What are immune privillaged sites and why are they

A

less subject to immune responses and attack (brain, eyes, testes, overy, placenta)

-rich in anti-inflammatory cytokines and high amounts of FasL

22
Q

What is immune deviation and an example of where it can happen and why

A

Shift in immune responses usually involving Th1/Th2 cells

-during pregnancy

23
Q

Why is placenta immune privaleged (5)

A
  • lack MHC1/2
  • expresses HLA-G (prevents NK cells)
  • expresses IDO
  • immune deviation
  • TGFb and IL10
24
Q

What is oral tolerance and what does it activate

A

peripheral tolerate induced by antigens given by mouth and exposed to gut mucosa

-may activate iTreg

25
Q

What is an underdeveloped oral tolerate associated w/

A

food allergy

PA2203- Mod 6 (9 decks)

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