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Immuno > Immunoregulation > Flashcards

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
Q

What is central tolerance?

A

Deletion of reactive self T cells in the thymus

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26
Q

What is peripheral tolerance?

A

the clonal anergy of mature T lymphocytes in the periphery

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27
Q

What is clonal anergy?

A

Inactivation (not death) of T cells due to the absence of costimulatory molecules

28
Q

Expression of self-antigens, in the absence of co-stimulator-producing inflammation (which would be seen during infection and injury), normally produces what?

A

Clonal anergy

29
Q

True or false: T lymphocyte tolerance is relatively long lasting

A

True

30
Q

True or false: B lymphocyte tolerance is relatively short-lived

A

True

31
Q

We have tolerance to lipids, polysaccharides etc, but T cells only recognize proteins. Explain this.

A

Tolerance of B lymphocytes

32
Q

When can reaction to self antigens occur in B lymphocyte maturation?

A

When only IgM is expressed at the surface of B cells, and they are exposed to antigen (immature stage)

33
Q

B cells get a “second chance” when they are found to express antibodies to self proteins. How?

A

Through receptor editing of light chain

34
Q

What is the effect of corticosteroids on Thymocytes?

A

Kills them =immunodeficiency

35
Q

What are the four populations of thymocytes in the thymus?

A
  1. CD4-CD8- (“double negative”)
  2. CD4+CD8+ (“double positive”
  3. CD4-CD8+
  4. CD4+CD8-
36
Q

Double positive thymocytes turn into what?

A

Mature thymocytes, with only one CD4/8 expressed

37
Q

What is positive selection?

A

Getting rid of T cells that cannot bind to self MHC proteins, or bind foreign ones.

38
Q

What is negative selection?

A

The process of getting rid of thymocytes that bind to self antigen

39
Q

What are the thymocytes that you want, and the body maintains after positive and negative selection?

A

thymocytes that recognize foreign protein and self MHC proteins

40
Q

What cells/where is negative selection carried out?

A

by dendritic cells at the cortico-medullary junction

41
Q

What is the AIRE gene, and what does it do?

A

Thymic gene the is responsible for the expression of tissue specific proteins (e.g. insulin), that allows for proper development of T lymphocytes

42
Q

Mutations in the AIRE gene lead to what?

A

widespread autoimmune disease

43
Q

The thymus atrophies with age. If there are remnants of it left, can it/they produce T lymphocytes?

A

Yes

44
Q

What are monokines? What produces it, what does it do?

A

Cytokine produced by mononuclear phagocytes to regulate the effector functions of phagocytic cells

45
Q

What are lymphokines? Functions (2)?

A

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
Q

What are colony stimulating factors (CSF)?

A

Cytokine produced by lymphocytes and mononuclear phagocytes to stimulate the production of granulocytes and monocytes in the bone marrow

47
Q

What are the three mechanisms of action for cytokines?

A

Autocrine
Paracrine
Endocrine

48
Q

How many cytokines are needed to regulate the production of other cytokines?

A

Just one

49
Q

How do cytokines initiate their action?

A

By binding to cellular receptors on target cells

50
Q

What is type I interferon composed of? What does it do? (3)

A

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
Q

What is Tumor necrosis factor (TNF)-α produced by?

A

Produced by mononuclear phagocytes and T lymphocytes in response to bacterial lipopolysaccharide (LPS or endotoxin).

52
Q

Very high concentrations of (TNF)-α produce what?

A

Septic shock

53
Q

What are the two chains that compose IFN?

A

alpha and beta

54
Q

What are the biological actions of IFN? (3)

A
  1. Inhibit viral replication via paracrine action
  2. Enhance cytolytic capabilities of NK cells
  3. Increase expression of class I MHC
55
Q

What produces tumor necrosis factor (TNF)-α?

A

Mononuclear phagocytes in response to bacterial LPS

56
Q

What are the five biological actions of (TNF)-α? (last one is extreme concentrations).

A
  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
Q

What produces IL-1?

A

Activated mononuclear phagocytes

58
Q

What is the biological action of IL-1? What about at high concentrations?

A

Induces the production of IL6

High conc = fever and wasting

59
Q

What produces IL-6? (3)

A

mononuclear phagocytes, endothelial cells, activated T cells?

60
Q

What are the biological actions of IL-6?

A
  1. Aids in differentiation of B cells to plasma cells

2. induces hepatocytes to synthesize plasma proteins, such as fibrinogen

61
Q

What produces IL-2?

A

CD4+ T cells in response to antigenic stimulation

62
Q

What are the biological effects of IL-2?

A
  1. Autocrine/paracrine growth factor for T cells

2. Induces NK cells to become LAKs

63
Q

What produces IL-4? What is its biological activity?

A

produced by CD4+ T cells and mast cells/basophils and induces B cell isotype switching to IgE production

64
Q

What produces Transforming growth factor-beta (TGF-beta)? (2)

A
  1. produced by activated T cells and activated mononuclear phagocytes
  2. Stromal cells
65
Q

What are the biological effects of TGF-beta? (3)

A
  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
Q

What cells produce Interferon-γ? (3)

A

mainly produced by CD4+ and CD8+ T cells, but NK cells can also produce it

67
Q

What are the biological effects of Interferon-γ?

A
  1. Activates macrophages by making them more microbicidal

2. Up-regulates MHCs

Immuno (16 decks)

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