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MICR221 > L15 T cells > Flashcards

L15 T cells Flashcards

1
Q

what happens at sites of infection and inflammation in tissue

A

Dendritic cells take up antigen and present it on MHC

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2
Q

where do DC go after being at a site of infection

A

move to the lymph node

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3
Q

where do the naïve T cells come from (before entering and circulating the lymph node)

A

high endothelial venules (HEV)

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4
Q

what happens between the naïve T cells and Dc in the lymph node

A

the T cells scan the DC for peptides present on MHC

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5
Q

what must a T cell have in order to be activated by a DC

A

the right receptor to recognise the peptide present on MHC

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6
Q

names of activated T cells

A

CD4 helper cells

CD8 helper cells

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7
Q

what do the cytokines produced by T cells do?

A

make macrophages more bactericidal

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8
Q

example of a cytokine T cells can produce

A

IFN- gamma

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9
Q

what do CD4 helper cells do

A

activate B cells

produce cytokines

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10
Q

What do CD8 T cells do after being exposed to cytokines released by CD4

A

become cytotoxic by producing perforin and granzyme (cell-killing enzymes)

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11
Q

what part of both T and B cell antigen receptors interact with the peptides expressed on MHC

A

variable regions

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12
Q

why is it important for antigen receptors to have variable regions

A

so that they bind a range of peptides

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13
Q

what is a CAR T cell

A

chimeric antigen receptor

-an artificial receptor that recognises cancer cell antigens and triggers the T cell to produce cancer antigens

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14
Q

what do naive T cells form from

A

stem cells

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15
Q

what do the naive T cells (stem cells) do before entering the thymus

A

circulate the blood

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16
Q

where are T cells educated

A

thymus

17
Q

what happens to T cells once in the thymus

A

stimulated to undergo rearrangement of the genes that code for the T cell receptors (mean receptors can be expressed)

18
Q

what is clonal expansion

A

when a T cell comes into contact with an antigen

-T cell divides like crazy

19
Q

what happens to the other T cell with different antigen receptors

A

no clonal expansion

-just stays silent

20
Q

what kind of cells in the thymus kill off unwanted T cells

A

nurse cells (specialised dc)

21
Q

what are developing thymocytes

A

very immature T cells

22
Q

what happens to the thymocytes while in the thymus

A

passed over thymic stroma which expresses self-peptide on MHC I and II
Ability to bind to self MHC is tested

23
Q

why is the thymus so useful when testing immature T cells

A

it produces a wide range of antigens found throughout the body

24
Q

what happens to T cells that don’t elicit a response to MHC with self-peptide

A

it is considered a useless T cell
death by neglect
left to die,

25
Q

what happens if the T cell has a moderate signal from the MHC self-peptide

A

positive selection

T cell continues out of the thymus

26
Q

what happens when the T cell elicits a strong response with the MHC self-peptide

A

cell is programed to die

27
Q

how do auto immune disorders come about

A

whne the self peptide is expressed at too low a level in the thymus and so the T cells that strong interact with it make it through the thymus and then interact elsewhere in the body

28
Q

what are the positive selected T cells called

A

self MHC restricted

29
Q

What problems can occur due to the different MHC between different people

A

Specific T cells for a virus can only interact with the MHC that expressed the virus when if the peptide is the same

30
Q

what is teh cause of transplant rejection

A

subset of mature T cells that recognise foreign MHC on the organ (5% of T cells)

31
Q

what percent of T cells are alloreactive

A

1-5%

32
Q

what happens during an allogenic reaction

A

T cells expand

33
Q

what happens during an allogenic reaction

A

T cells react strongly to foreign MHC that is loaded with self peptide from the donor organ

34
Q

how are transplant rejections prevented

A

matching MHC

or powerful immuno suprresant to knock back the T cells

35
Q

transplant reactions occur due to

A

polymorphic MHC

36
Q

what does xenogeneic mean

A

different species

37
Q

what does autologous mean

A

self to self

38
Q

what does syngeneic mean

A

identical twins

39
Q

what does allogeneic reaction mean

A

self to non-identical of same species

MICR221 (23 decks)

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