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Semester Three > IIH L13-15 T cell block > Flashcards

IIH L13-15 T cell block Flashcards

1
Q

What is tolerance? L13

A

Process of eliminating or neutralising self-reactive lymphocytes

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2
Q

What cell types are considered thymus stromal cells? L13

A

Cortical and medullary epithelial cells and dendritic cells

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3
Q

What type of thymocytes are in the cortex? L13

A

Immature

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4
Q

What type of thymocytes are in the medulla? L13

A

Mature

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5
Q

What happens in the thymic cortex and what is the predominant cell type? L13

A

TCR gene rearrangement and (+) selection

Reticular epithelial cells

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6
Q

What happens in the thymic medulla and what is the predominant cell type? L13

A

(-) selection

Thymic epithelial cells expressing the AIRE gene which allows peripheral tolerance

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7
Q

What is (+) selection? L13

A

Allows T cells that recognise foreign antigen to mature, done by cortical epithelial cells. T cells that fail to recognise antigen die by neglect

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8
Q

What is (-) selection? L13

A

Removes potentially auto-reactive T-cells that recognise self-peptides; mediated by medullary dendritic cells

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9
Q

What cell type is present at the cortico-medullary junction in the thymus and what is its function? L13

A

Macrophages prevent damaged/dying cells from passing to the medulla

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10
Q

What percentage of T cells survive the selection processes in the thymus? L13

A

5%

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11
Q

Where are the two sites of immune ignorance in the body? L13

A

Eye and testes

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12
Q

What is the function of T-reg cells? L13

A

Prevent auto-reactive T cells from causing damaging immune responses

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13
Q

What is clinical autoimmunity? L14

A

Consequence of loss of tolerance

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14
Q

What are the three mechanisms for loss of tolerance? L14

A

Sites of ignorance (testes and eye)
Failure of Treg cells
Inappropriate antigen presentation

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15
Q

What are some ways that autoantibodies can cause damage? L14

A

Lysis of self cells

Immune complex formation

Blockade of receptors for physiological ligands e.g. Myaesthenia Gravis and Pernicious Anaemia

Stimulation of cell surface receptors e.g. Graves disease (ABs imitate TSH)

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16
Q

What is Goodpasture’s syndrome? L14

A

Autoantibodies against lung and kidney basement membranes

17
Q

What happens in rheumatoid arthritis? L14

A

Systemic inflammatory disease
Autoantibodies against Fc portion of IgG
Anti-CCP antibodies

18
Q

Which cells are principally infected by bacterial pathogens? L15

A

Monocytes and macrophages

19
Q

How do bacterial pathogens avoid the immune response? L15

A

Rupture early phagosome and escape into cytosol
OR
Block fusion of phagosome and lysosome

20
Q

Which cytokines are released by dendritic cells that promote activation and differentiation of naive CD4 and CD8 cells? L15

A

IL-12 and IL-18

21
Q

What do CD4 Th1 cells release in response to bacterial pathogens? L15

A

IFNγ and TNFα

22
Q

What does IFNγ promote? L15

A

Macrophage activation

23
Q

When macrophages are activated what is there increased expression of? L15

A

MHC I & II
CD40
CD80
ROS

24
Q

What primes Th1 cells? L15

A

MHC II presentation

25
Q

How do Th1 cells kill bacteria? L15

A

Reactive Oxygen Species and Nitric Oxide

26
Q

What do CD8 cytotoxic T cells release in response to bacterial pathogens? L15

A

Cytotoxic granules containing granzyme, perforin and granulysin

27
Q

What primes cytotoxic T cells? L15

A

MHC I

28
Q

Antigens from what type of bacteria express MHC I? L15

A

Cytosolic bacteria

29
Q

Antigens from what type of bacteria express MHC II? L15

A

Vacuole-resistant bacteria

30
Q

Symptoms of TB? L15

A

Breathlessness, appetite loss, haemoptysis, cough, weight loss

31
Q

Mycobacterium tuberculosis inhibits which innate killing mechanisms? L15

A

ROS and NO radical generation

Phago-lysosome fusion

32
Q

Name an example of a Delayed Hypersensitivity Test. L15

A

Positive Mantoux test

33
Q

Function of TNFα? L15

A

Increased adhesion molecule expression and local tissue destruction

34
Q

When does a granuloma form? L15

A

From a chronic DTH reaction, when the antigen is unable to be eliminated

35
Q

What is competitive with CD28 for DC costimulation to prevent over-stimulation of T cells? l13

A

CTLA4

36
Q

What does CD40 on a DC bind to on a T helper cell? L13

A

CD40 ligand

37
Q

What does CD28 on a T helper cell bind to on a DC? L13

A

CD80/86

38
Q

When are Th2 cells used?

A

Parasitic infections

39
Q

Which cytokines are released by Th2 cells in respond to parasitic infections?

A

IL-4 and IL-13

Semester Three (12 decks)

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