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Immunoregulation Flashcards

1
Q

What are the cell surface markers of T-regs?

A

CD4+, FoxP3+, and CD25

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2
Q

What is CD 25?

A

The alpha chain of IL-2 receptor

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3
Q

What is IL-2’s role in Treg cells?

A

Growth factor for Treg cells

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4
Q

What is IPEX syndrome?

A

An absence of T reg cells, causing autoimmunity d/t overstimulation of immune system

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5
Q

What is the function of CTLA-4?

A

Inhibits the activation of T cells by blocking the B7 receptor found on antigen presenting cells

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6
Q

What is TGF-β’s role in Treg development?

A

Induces the expression of FoxP3

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7
Q

What are the two general functions of Treg cells?

A
  1. prevent excessive immune responses to foreign antigens

2. prevent immune responses to self-antigens missed by tolerization

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8
Q

What cytokines do Treg cells express?

A

IL-10 and TGF-β

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9
Q

What is the function of IL-10 expressed from Treg cells? (2)

A

inhibits IL-12 production by dendritic cells and macrophages and downregulates expression of costimulatory molecules and class II MHC by these cells

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10
Q

What is the function of TGF-β expressed by Treg cells? (2)

A

suppresses the activation of macrophages and T cells and promotes the development of Treg cells

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11
Q

What role does IL-2 play in Treg cells mechanism of action?

A

Treg cells consume it, inhibiting development of other cells

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12
Q

What is an idiotype?

A

an antibody’s antigen-binding site made up of the hypervariable regions of the heavy and light chains

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13
Q

What is an anti-idiotope? What is the function of anti-idiotopes?

A

an antibody to another antibody’s idiotope

bind to and inhibit the B lymphocytes that express the original idiotope

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14
Q

How do anti-idiotypes work?

A

Produced a few days after antibody to antigen are produced. Not understood how

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15
Q

What are the two ways in which antibodies produced by B cells can inhibit B cells?

A
  1. Bind up/eliminate all antigen

2. Complexes of Antibodies bind to Fc receptors and membrane antibody

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16
Q

What is tolerance in immunology?

A

is a block in the growth and differentiation of lymphocytes brought about by antigen

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17
Q

Loss of tolerance leads to what?

A

Autoimmune diseases

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18
Q

Is tolerance antigen specific?

A

Yes

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19
Q

Is tolerance aquired or inborn?

A

Acquired

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20
Q

Do all individuals have the ability to develop antibodies to self antigens?

A

Yes

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21
Q

Is it easier to tolerize immature lymphocytes or mature ones?

A

Immature ones

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22
Q

What are the two mechanisms of tolerance?

A
  1. Clonal Deletion

2. Functional inactivation (clonal anergy)

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23
Q

Can mature lymphocytes be tolerized to antigen?

A

Yes

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24
Q

Why are T lymphocytes a better target of regulation than B cells?

A

They are more central to activation of immune response

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25
What is central tolerance?
Deletion of reactive self T cells in the thymus
26
What is peripheral tolerance?
the clonal anergy of mature T lymphocytes in the periphery
27
What is clonal anergy?
Inactivation (not death) of T cells due to the absence of costimulatory molecules
28
Expression of self-antigens, in the absence of co-stimulator-producing inflammation (which would be seen during infection and injury), normally produces what?
Clonal anergy
29
True or false: T lymphocyte tolerance is relatively long lasting
True
30
True or false: B lymphocyte tolerance is relatively short-lived
True
31
We have tolerance to lipids, polysaccharides etc, but T cells only recognize proteins. Explain this.
Tolerance of B lymphocytes
32
When can reaction to self antigens occur in B lymphocyte maturation?
When only IgM is expressed at the surface of B cells, and they are exposed to antigen (immature stage)
33
B cells get a "second chance" when they are found to express antibodies to self proteins. How?
Through receptor editing of light chain
34
What is the effect of corticosteroids on Thymocytes?
Kills them =immunodeficiency
35
What are the four populations of thymocytes in the thymus?
1. CD4-CD8- ("double negative") 2. CD4+CD8+ ("double positive" 3. CD4-CD8+ 4. CD4+CD8-
36
Double positive thymocytes turn into what?
Mature thymocytes, with only one CD4/8 expressed
37
What is positive selection?
Getting rid of T cells that cannot bind to self MHC proteins, or bind foreign ones.
38
What is negative selection?
The process of getting rid of thymocytes that bind to self antigen
39
What are the thymocytes that you want, and the body maintains after positive and negative selection?
thymocytes that recognize foreign protein and self MHC proteins
40
What cells/where is negative selection carried out?
by dendritic cells at the cortico-medullary junction
41
What is the AIRE gene, and what does it do?
Thymic gene the is responsible for the expression of tissue specific proteins (e.g. insulin), that allows for proper development of T lymphocytes
42
Mutations in the AIRE gene lead to what?
widespread autoimmune disease
43
The thymus atrophies with age. If there are remnants of it left, can it/they produce T lymphocytes?
Yes
44
What are monokines? What produces it, what does it do?
Cytokine produced by mononuclear phagocytes to regulate the effector functions of phagocytic cells
45
What are lymphokines? Functions (2)?
Cytokines produced by activated T lymphocytes to aid in the activation and differentiation of lymphocyte subsets as well as control the activity of macrophages, neutrophils, and eosinophils
46
What are colony stimulating factors (CSF)?
Cytokine produced by lymphocytes and mononuclear phagocytes to stimulate the production of granulocytes and monocytes in the bone marrow
47
What are the three mechanisms of action for cytokines?
Autocrine Paracrine Endocrine
48
How many cytokines are needed to regulate the production of other cytokines?
Just one
49
How do cytokines initiate their action?
By binding to cellular receptors on target cells
50
What is type I interferon composed of? What does it do? (3)
Composed of alpha and beta IFN 1. Inhibits viral replication 2. Enhance NK cell action 3. Increase cellular expansion of class I MHC molecules
51
What is Tumor necrosis factor (TNF)-α produced by?
Produced by mononuclear phagocytes and T lymphocytes in response to bacterial lipopolysaccharide (LPS or endotoxin).
52
Very high concentrations of (TNF)-α produce what?
Septic shock
53
What are the two chains that compose IFN?
alpha and beta
54
What are the biological actions of IFN? (3)
1. Inhibit viral replication via paracrine action 2. Enhance cytolytic capabilities of NK cells 3. Increase expression of class I MHC
55
What produces tumor necrosis factor (TNF)-α?
Mononuclear phagocytes in response to bacterial LPS
56
What are the five biological actions of (TNF)-α? (last one is extreme concentrations).
1. Activates mononuclear phagocytes and PMNs 2. Increases adhesiveness of vascular epithelium 3. Generates fever 4. Induction of neutrophilia 5. Shock/DIC at high levels
57
What produces IL-1?
Activated mononuclear phagocytes
58
What is the biological action of IL-1? What about at high concentrations?
Induces the production of IL6 High conc = fever and wasting
59
What produces IL-6? (3)
mononuclear phagocytes, endothelial cells, activated T cells?
60
What are the biological actions of IL-6?
1. Aids in differentiation of B cells to plasma cells | 2. induces hepatocytes to synthesize plasma proteins, such as fibrinogen
61
What produces IL-2?
CD4+ T cells in response to antigenic stimulation
62
What are the biological effects of IL-2?
1. Autocrine/paracrine growth factor for T cells | 2. Induces NK cells to become LAKs
63
What produces IL-4? What is its biological activity?
produced by CD4+ T cells and mast cells/basophils and induces B cell isotype switching to IgE production
64
What produces Transforming growth factor-beta (TGF-beta)? (2)
1. produced by activated T cells and activated mononuclear phagocytes 2. Stromal cells
65
What are the biological effects of TGF-beta? (3)
1. inhibits T cell proliferation and differentiation into CTL's as well as inhibits macrophage activation. 2. induces B cells to produce IgA antibody 3. Initiates wound healing
66
What cells produce Interferon-γ? (3)
mainly produced by CD4+ and CD8+ T cells, but NK cells can also produce it
67
What are the biological effects of Interferon-γ?
1. Activates macrophages by making them more microbicidal | 2. Up-regulates MHCs

Immuno (16 decks)

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