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CST - BIOSCI107 > B & I - Cell Mediated Immunity and MHC > Flashcards

B & I - Cell Mediated Immunity and MHC Flashcards

1
Q

where do immature lymphocytes from bone marrow travel to to mature

A

thymus

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2
Q

what surface antigens are expressed in this immature stage

A

CD4 and CD8

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3
Q

they encounter MHC ______ __ and _____ __ molecules expressed on thymic epithelium and respond accordingly or die by neglect

A

class I and class II

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4
Q

If they respond to MHC class II they become?

A

CD4 helper T cells

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5
Q

If they respond to MHC class I they become?

A

CD8 cytotoxic T cells (CTL) and their fate is sealed in the thymus before they exit into the blood stream

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6
Q

what do the CD4 helper cells do

A

respond by secreting cytokines

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7
Q

what do the CD8 cytotoxic cells do

A

kill other infected cells

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8
Q

what are the 4 subsets of CD4 helper

A

treg
Th1
Th2
Th17

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9
Q

what does treg do

A

suppresses the immune response

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10
Q

what does Th1 do

A

promotes cell-mediated immunity

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11
Q

what does Th2 do

A

promotes antibody mediated immunity

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12
Q

what does Th17 do

A

promotes inflammation

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13
Q

what type of organ is the thymus and when is it the largest

A

it is a primary lymphoid organ that is largest at birth and shrinks with age

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14
Q

where is the thymus located

A

sits at the top of the pericardium above the heart

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15
Q

haemopoietic lymphoid precursors migrate from the bone marrow to the thymus where they mature into ?

A

T lymphocytes

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16
Q

only a small percentage of T cells survive the thymus as mature T cells, most die from

A

neglect

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17
Q

T cell that survive the thymus have been educated to do what

A

educated to recognise self MHC molecules expressed in thymic tissue

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18
Q

viruses replicate ____ cells

A

inside

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19
Q

immune system is regulated by a set of?

what do these genes make up

A

highly polymorphic genes that were first identified as controlling tissue transplantation - these genes make up the MHC (Major Histocompability Complex)

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20
Q

what do these genes code for

A

human leukocyte antigens (HLA ) on the cell surface

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21
Q

unlike antibodies, the TcR recognises only ___ antigen

A

one

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22
Q

what antigen does the TcR recognise and why

A

the proteins of the MHC because the T cells were selected during thymic development for their ability to respond to self MHC molecules

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23
Q

unlike Ig, the TcR (does/does not?) under go affinity maturation

A

does not

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24
Q

why does TcR not undergo affinity maturation

A

because you don’t want the affinity of TcR to increase to a self antigen

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25
Q

When do cytotoxic T cells (CTL) react to your own cells

A

when there is a change in MHC class I molecules - i.e. when the express a “neo-antigen” picked up from inside the cell

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26
Q

the “neo-antigen” can be a ____ or _____ ___ antigen

A

viral

altered self

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27
Q

what do histocompatibility genes control

A

viral immunity

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28
Q

what are the two antigens viral immunity requires

A

self and non-self

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29
Q

what are self antigens

A

antigens encoded by MHC

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30
Q

what are non-self antigens

A

antigens encoded by the virus

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31
Q

what do T cells detect

A

small fragments of virus picked up inside the cell and expressed in the binding groove of MHC molecules on the cell surface

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32
Q

viral immunity depends on ____ to present antigens

A

MHC

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33
Q

what is the T cell receptor

A

a membrane bound Ig-like molecule on T lymphocytes

34
Q

HLA molecules are expressed on most cells and present what to T cells?

A

peptide antigens

35
Q

Are HLA molecules polymorphic

A

yes they are highly polymorphic

36
Q

what does the antigen binding surface of the TcR bind to

A

the top of MHC which represent the “peptide groove”

37
Q

what does the peptide groove contain

A

the foreign peptide antigen

38
Q

the TcR has affinity towards ?

A

the combination of MHC

39
Q

MHC refers to ?

A

the genetic locus that regulates histocompatibility

40
Q

HLA refers to ?

A

the 6 different molecules expressed on human cells

41
Q

H2 refers to ?

A

the antigens on mouse cells

42
Q

What are the three human Class I molecules

A

A B C

43
Q

what are the three human class II molecules

A

DR, DP, DQ

44
Q

what are CD4 and CD8

A

accessory molecules that physically associate with the TcR

45
Q

what do CD4 helper T cells do in this context

A

recognise antigens in MHC class II

46
Q

what do CD8 cytotoxic T cells

A

recognise antigens in MHC class I

47
Q

what component of CD4 and CD8 initiates T cell signalling

A

CD4 and CD8 have intracellular tyrosine kinases associated with their cytoplasmic tails that initiate T cell signalling through phosphorylation.

48
Q

what are CD4 and CD8 crucial for

A

immune activation

49
Q

CD4 and CD8 are ___________ that define two ______ _______ __ _ __________

A

co-receptors

important subsets of T lymphocytes

50
Q

peptide source of MHC class I

A

intracellular

51
Q

pathogen in MHC class I

A

viruses

52
Q

responding T cells in MHC class I

A

CD8

53
Q

effector function of MHC class I

A

cytotoxic

54
Q

Peptide source of MHC class II

A

extracellular

55
Q

pathogen of peptide source MHC class II

A

bacteria

56
Q

responding T cells of MHC class II

A

CD4

57
Q

effector function of MHC class II

A

help

58
Q

T cells ______ and produce _______ that ____ other cells

A

proliferate
produce
help

59
Q

what does CTL produce that punches holes and destroys cell viability (and what does it punch holes in)

A

CTL produces granzyme and perforins that punch holes in the target cell membrane and destroy
cell viability

60
Q

there are hundreds of different amino acid variations at each ____ _______

A

MHC locus

61
Q

polymorphism is restricted to

A

the protein domains that form the peptide groove

62
Q

what genes and molecules does an individual express

A

both maternal and paternal genes 2 x 3 MHC class I A B C and 2 x 3 MHC class II DR DP DQ molecules

63
Q

how are the genes and molecules in an individual expressed

A

with co-dominance

64
Q

how many polymorphic molecules are expressed on cells

A

12

65
Q

can two people have the same MHC profile

A

no everyone is completely different (identical twins excluded)

66
Q

why can’t tissue be transplanted from one person to another

A

because of MHC polymorphism - T cells from the recipient recognise the donor MHC antigens as foreign

67
Q

what must people who get transplants do

A

take an immunosuppressive drug for the rest of their lives to suppress the T cell response

68
Q

what are the two major consequences of MHC polymorphism

A

1) tissue transplantation is difficult except for identical twins. this requires careful matching and immunosuppressive drugs.
2) MHC polymorphism are strongly linked to many autoimmune diseases.

69
Q

why is MHC so strongly associated with many autoimmune diseases

A

because the MHC locus is the only polymorphic part of your entire genome

70
Q

in autoimmune disease, what are your T cells doing?

A

reacting to self-antigens that are best presented by these MHC molecules

71
Q

MAIN POINT: what is MHC

A

a set of highly polymorphic genes coding for a group of membrane molecules called HLA in humans

72
Q

MAIN POINT: the TcR is an Ig like membrane molecule with a gene locus that is

A

segmented and undergoes rearrangement

73
Q

MAIN POINT: Graft rejection was used to create? what did this show?

A

congenic strains of mice that were then used in a famous experiment showing that viral immunity requires both self MHC and foreign antigen

74
Q

MAIN POINT: MHC molecules come in which two types and what do both have

A

class I and class II

both have a peptide binding groove that holds a foreign peptide

75
Q

MAIN POINT: T cells are divided into two functionally different populations marked by the?

A

CD4 and CD8 antigens

76
Q

MAIN POINT: CD4 and CD8 are accessory molecules associated with the T cell receptor responsible for

A

intracellular signalling through associated tyrosine kinases

77
Q

MAIN POINT: CD8+ T cells are _____ and recognise _____ antigens presented by MHC class _

A

cytotoxic
viral antigens
MHC class I

78
Q

MAIN POINT: CD4+ T cells are _____ ___ ___ and recognise _____ antigens presented by MHC class _

A

helper T cells
bacterial antigens
MHC class II

79
Q

MAIN POINT: why is tissue transplantation so difficult

A

MHC polymorphism

80
Q

MAIN POINT: Why are MHC polymorphisms so strongly linked to many disease susceptibilities

A

because it is the only part of your genome that is so polymorphic

CST - BIOSCI107 (13 decks)

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