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Flashcards in Immunoregulation Deck (67):
1

What are the cell surface markers of T-regs?

CD4+, FoxP3+, and CD25

2

What is CD 25?

The alpha chain of IL-2 receptor

3

What is IL-2's role in Treg cells?

Growth factor for Treg cells

4

What is IPEX syndrome?

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

5

What is the function of CTLA-4?

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

6

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

Induces the expression of FoxP3

7

What are the two general functions of Treg cells?

1. prevent excessive immune responses to foreign antigens

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

8

What cytokines do Treg cells express?

IL-10 and TGF-β

9

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

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

10

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

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

11

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

Treg cells consume it, inhibiting development of other cells

12

What is an idiotype?

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

13

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

an antibody to another antibody's idiotope

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

14

How do anti-idiotypes work?

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

15

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

1. Bind up/eliminate all antigen
2. Complexes of Antibodies bind to Fc receptors and membrane antibody

16

What is tolerance in immunology?

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

17

Loss of tolerance leads to what?

Autoimmune diseases

18

Is tolerance antigen specific?

Yes

19

Is tolerance aquired or inborn?

Acquired

20

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

Yes

21

Is it easier to tolerize immature lymphocytes or mature ones?

Immature ones

22

What are the two mechanisms of tolerance?

1. Clonal Deletion
2. Functional inactivation (clonal anergy)

23

Can mature lymphocytes be tolerized to antigen?

Yes

24

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

They are more central to activation of immune response

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