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BIOSCI 107 Part Two > Blood and Immune: Cellular Immunity and Histocompatibility > Flashcards

Blood and Immune: Cellular Immunity and Histocompatibility Flashcards

1
Q

Where do T lymphocytes mature

A

the thymus

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2
Q

where do the precursor of T cells get produced before migrating to the thymus

A

bone marrow

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3
Q

What is a thymocyte

A

Immature T cell found in the thymus

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4
Q

The coreceptors (cell surface markers) on a T cell

A

CD4+, CD8+ (or just CD4 and CD8)

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5
Q

What is the name for a T cell expressing both CD4 and CD8 on its surface

A

a double positive immature thymocyte

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6
Q

Name of T cells that only express CD4+

A

CD4+ helper T cells

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7
Q

Name of T cells that only express CD8+

A

CD8+ cytotoxic T cells

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8
Q

What % of T lymphocytes in blood are CD8+ + cytotoxic

A

20%

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9
Q

What % of T lymphocytes in blood are CD4+ helper

A

80%

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10
Q

The four subgroups of CD4 T helper cells

A

Treg, Th1, Th2, Th17

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11
Q

What is the function of Tregs

A

to regulate immune response

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12
Q

What is the function of Th1

A

drive cellular response

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13
Q

What is the function of Th2

A

drive antibody response (B cells)

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14
Q

What is the function of Th17

A

control inflammatory response

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15
Q

If a pathogen demands a cellular immune response, which T helper cell subgroup will predominate?

A

Th1

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16
Q

How are T cells distinguished

A

by their antigen (CD4 or CD8)

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17
Q

What is CD in CD4 and CD8

A

cluster differentiation

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18
Q

How can T cells be marked

A

by the monoclonal antibody that binds to the antigen CD4 or CD8

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19
Q

When is the thymus at its largest size and why

A

largest at birth then shrinks with age (cellular immune response developed before and just after birth)

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20
Q

What is the function of the thymus

A

Location where T cells are ‘educated’ to recognise self MHC molecules and where they become CD4 or CD8 (its important in immune response development)

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21
Q

Where is the thymus located

A

It sits at the top of the pericardium above the heart

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22
Q

Name of precursor to T lymphocytes

A

Hematopoietic lymphoid precursors

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23
Q

What is negative selection

A

when T cells die from “neglect”, have not recognised the correct antigen to activate and undergo mitosis

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24
Q

What is positive selection

A

Some cells recognise the correct antigen but are activated too strongly which are killed by apoptosis

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25
Q

What is Apoptosis

A

is a form of programmed cell death, or “cellular suicide

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26
Q

What happens to T cells that survive the thymus

A

“educated” to recognise self MHC molecules expressed in thymic tissue

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27
Q

What system is MHC important for

A

adaptive immune response/system

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28
Q

What type of pathogens are viruses

A

intracellular

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29
Q

Where do viruses replicate

A

inside cells

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30
Q

What do T cells do when they recognise infected cells

A

either kill them or provide help to other cells that reduce the ability of the virus to replicate and produce copies of itself which infect other cells

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31
Q

What does MHC stand for

A

Major Histocompatibility Complex

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32
Q

What is MHC

A

A set of highly polymorphic genes that code for Human Leukocyte Antigens on the cell surface

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33
Q

What antigen on a cell will express parts of a virus if infected

A

MHC

34
Q

What antigen controls tissue transplantation

A

MHC

35
Q

What is and isn’t “self”

A

MHC, “not self” is if MHC changed (due to virus or bacteria)

36
Q

What does CTL stand for

A

Cytotoxic T lymphocytes (CD8 T cells)

37
Q

Function of CTL

A

stimulate immune response which actively kills cells

38
Q

What do CTL generate?

A

perforin molecules that are inserted into target cells to kill them

39
Q

What do CTL do if they recognise a “non-self cell”

A

CTL binds tightly to cells that have altered class 1 MHC (expressing a neo-antigen that is viral or altered self antigen) and release perforin molecules which form pores into target cells causing the release of internal innards of the cell = cell death

40
Q

What is a neo-antigen

A

are mutated antigens specifically expressed by tumour tissue and are not expressed on the surface of normal cells

41
Q

meaning of congenic

A

Strains that are genetically identical except for one or more MHC locus/loci

42
Q

What are congenic mice

A

Congenic mice is when you isolate particular genes that regulate certain phenotypes (e.g. tissue rejection)

43
Q

What is MHC restriction

A

The fact that a T cell can interact with a self-MHC molecule and a foreign peptide bound to it, but will only respond to the antigen when it is bound to a particular MHC molecule

44
Q

viral immunity requires both these antigens

A 
SELF Antigen(s) encoded by MHC 
NON-SELF Antigen(s) encoded by the virus
45
Q

what is HLA

A

human leukocyte antigen coded for by MHC

46
Q

What does a T cell form with a target cell?

A

synapse so it can insert signal into target cell so it undergoes apoptosis

47
Q

How is MHC changed by a target cell

A

MHC has been changed because of a new peptide antigen that has been inserted into groove on the top of the MHC (HLA) molecule

48
Q

What a T cell receptor

A

a membrane bound Ig-like molecule on T lymphocytes

49
Q

Classes of MHC

A

class 1 and 2

50
Q

Names of antigen/loci in class 1

A

A, B and C

51
Q

Names of antigen/loci in class 2

A

DR, DP, DQ

52
Q

How many types of each antigen in both class 1 and 2 exist

A

two possible types (paternal and maternal alleles)

53
Q

How many types of antigens in total are expressed on the surface of cells

A

12

54
Q

What does H2 refer too

A

the MHC antigens on mouse cells

55
Q

What can MHC molecules be used for in medicine

A

you can transplant and store tissues in case someone needs a bone marrow transplant

56
Q

What part of MHC class 1 is polymorphic

A

the top (the 2 alpha helices on top of the heavy chain), amino acid sequences vary from individuals

57
Q

Where does a viral peptide sit in MHC class 1

A

in groove between the two alpha helices

58
Q

What part of MHC class 1 is invariant

A

lower part (bound by CD8)

59
Q

What holds MHC class 1 molecules in the right conformation

A

Beta 2M

60
Q

What part of MHC class 2 is polymorphic

A

The top (1 beta and 1 alpha strand)

61
Q

Where does a viral peptide sit in MHC class 2

A

in groove between alpha and beta strand

62
Q

Is the viral peptide longer in class 1 or 2

A

class 2

63
Q

Where does viral peptide come from in MHC class 1

A

from virus inside the cell or altered self antigen

64
Q

Where does viral peptide come from in MHC class 2

A

antigens that have come from extracellular pathogens like bacteria that have been taken up by phagocytosis and broken down so pieces attach groove

65
Q

What type of cell recognises antigens in MHC class 1

A

CD8 cytotoxin T cells

66
Q

What type of cell recognises antigens in MHC class 2

A

CD4 Helper T cells

67
Q

What is intracellular tyrosine kinases

A

CD8 and CD4 have these receptors associated with their cytoplasmic tails. These initiate T cell signalling through phosphorylation

68
Q

What do CD4+ T Helper cells do when they recognise MHC class 2 antigens

A

T cells proliferate and produce cytokines that “help” other cells

69
Q

What do CD8+ T Helper cells do when they recognise MHC class 1 antigens

A

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

70
Q

Type of pathogen antigen expressed by MHC class 1

A

virus

71
Q

Type of pathogen antigen expressed by MHC class 2

A

bacteria

72
Q

Peptide source in MHC class 1

A

intracellular

73
Q

Peptide source in MHC class 2

A

extracellular

74
Q

What is polymorphism

A

genes that encode for the MHC complex are all different across individuals

75
Q

Is tissue rejection learned

A

yes

76
Q

What are haplotypes

A

a set of genetic determinants located on a single chromosome (lots of differing variations of aa sequence at each MHC locus)

77
Q

What is polymorphism restricted to

A

the protein domains that form the peptide groove

78
Q

What are anchor amino acids

A

the few points in peptides that are invariant (amino acid side chains point down into MHC molecule and anchor)

79
Q

What is the evolutionary purpose of polymorphism in MHC

A

Polyphormism is designed to create the broadest capacity for protection of a species as a whole (MHC in a community is for what they are most likely to encounter). When communities do not have the right MHC haplotypes, new diseases can devastate communities

80
Q

Two major consequences of MHC polymorphism

A

Tissue transplantation and autoimmune diseases

81
Q

What did the congenic mice experiment show

A

viral immunity requires both self MHC and foreign antigen

BIOSCI 107 Part Two (17 decks)

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