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Medicine Unit 3 > Adaptive immunity > Flashcards

Adaptive immunity Flashcards

1
Q

adaptive immunity basic

A

specific to a pathogen
slower

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2
Q

humoral immunity within adaptive

A

proteins dissolved in serum, plasma nd tissue fluid
antibodies

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3
Q

cells involved in adaptive immunity

A

b cells
antibodies
t cells
effector t cells
memory t and B cells

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4
Q

where do the 3 main types of lymphocyte originate from

A

common lymphoid precursor

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5
Q

lymphocytes that make ups the adaptive immune system

A

T and B cells
recognise specific antigen
proliferate and differentiate to mediate effector function
provide immunological memory

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6
Q

antigens

A

parts of pathogens (often proteins or parts of proteins) to which T and B cells respond
they respond via their antigen receptor
which is highly specific i

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7
Q

lymphocyte antigen receptors

A

unique antigen receptor on each lymphocyte
large diversity of specificities in T and B cell populations

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8
Q

what is antigen recognition by a specific lymphocyte linked to

A

activaiton
proliferation
differentiation
results in many specific cells with effector function

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9
Q

T cell responding simple

A

cytotoxicity
help of other cells
regulation

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10
Q

B cells responding simple

A

antibodies (neutralisation, opsonisation, activation of complement)

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11
Q

memory T and B cells

A

long-lived and triggers a quicker and more effective immune response on second infection with the same pathogen

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12
Q

primary lymphoid organs

A

bone marrow and thymus
where lymphocytes develop and mature from bone marrow-derived stem cells

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13
Q

secondary lymphoid organs

A

lymph nodes, spleen, MALT
site where adaptive immune responses are coordinated

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14
Q

T cells

A

originate in the bone marrow
mature in the thymus
express antigen receptor known as T cell receptor (TCR)
TCR recognises peptides presented to it
in the right conditions, T cell breaking TCR recognising the presented peptide becomes activated, proliferates and differentiates into lots of cells which have effector function

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15
Q

5 steps of T cell immune response

A

diversity
specific recognition
activation
proliferaiton and differentiation
response by effector cells

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16
Q

TCR diversity

A

genetic mechanism evolved to create diversity of specificities in the adaptive immune system

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17
Q

schematic structure of the T cell receptor

A

heterodimeric receptor
2 different chains, alpha and beta

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18
Q

with diversity why are many TCR not suitable

A

some useless: don’t bind peptides presented by molecules on your cells
dangerous: bind self-peptides very strongly

cells bearing these TCR die during T cell development in the thymus

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19
Q

T cell specific recognition

A

antigen must be broken down into peptide fragments
epitope peptide binds to a self molecule, MHC molecule
TCR binds to complex of MHC molecule and epitope peptide

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20
Q

2 main types of T cells

A

helper T cells
cytotoxic T cells

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21
Q

helper T cells: MHC, co-receptor and function

A

MHC 2 (presents antigen only on professional antigen presenting cells)
CD4
produces cytokines to activate others immune cells
express surface molecules to affect other cell types

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22
Q

cytotoxic T cells: MHC, co-receptor and function

A

MHC 1 (presents antigen on all body cells)
CD8
]kill virus-infected cells directly

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23
Q

which T cell is in the image

A

CD4 T cell

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24
Q

which T cell is in the image

A

CD8 T cell

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25
Q

example of an antigen presenting cell

A

dendritic cell
it is professional
key role in initiating adaptive immunity by linking innate to adaptive

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26
Q

key features of dendritic cells

A

specialised for antigen uptake and presentation
mature when stimulated by PAMPs and DAMPs

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27
Q

how are dendritic cells specialised for antigen uptake and presentation

A

dendritic cells present antigen open both MHC class 1and 2
sp they can activate CD8 and CD4 T cells

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28
Q

how are dendritic cells matured when stimulated by PAMPs and DAMPs

A

cause them to express high levels of molecules required to activate naive T cells
migrate to secondary lymphoid tissue which is a specialised structure for initiation of adaptive immunity

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29
Q

how are professional APC specialised to initiate adaptive immunity

A

provide all the signal necessary to activate naive T cells
express MHC 1 and 2 so can activate CD8 and CD$

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30
Q

nucleated cells, MHC class?

A

all express MHC class 1
means when infected they can present pathogen-derived antigens and be targets of CD8 cytotoxic T cells

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31
Q

other examples of professional APC

A

macrophages and B cells

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32
Q

what are MHCs and HLAs

A

MHC: major histocompatibility complex
HLA: human leukocyte antigens

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33
Q

large proteins antigens

A

digested into small peptides, epitopes of the antigen

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34
Q

where are peptide epitopes bound to

A

in the peptide-binding groove of the HLA encoded by MHC genes

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35
Q

HLA in MHC class 1

A

A,B and C

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36
Q

HLA in MHC class 2

A

DP, DR and DQ

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37
Q

which MHC class is this

A

class 1
expressed by all nucleated cells
binding groove holds short peptides, 8-10 amino acids

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38
Q

which MHC class is this

A

class 2
expressed by APCs
binding groove holds larger peptides, 13-17

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39
Q

mhc genes

A

polygeny
polymorphism

40
Q

polygeny

A

several MHC genes

41
Q

polymorphism

A

variation in population- protection at population level

42
Q

MHC 1 presentation

A

infection of body cell by virus
virus is chopped up by the proteasome
new viral particles are synthesised in the ER
antigens landed onto the MHC 1 in the endoplasmic reticulum
activates CD8 cytotoxic T cells

43
Q

MHC 2 presentations

A

phagocytosis of pathogen by antigen presenting cell
pathogen is chopped up by phagolysosomes
antigens loaded onto MHC 2 in the phagolysosome
activates CD4 helper T cells

44
Q

signals that naive T cells need to be activated

A

antigen binding to the T cell receptor
costimulation
cytokines

45
Q

first signal of T cell

A

peptide-MHC : TCR
if there is a recognition then an immune synapse forms

46
Q

second signal of the T cell

A

costimulation
B7: CD28

47
Q

third single of T cells

A

cytokines
APC produces cytokines that instruct the T cell to differentiate into the right type of effector T cell to destroy the pathogen

48
Q

outcomes of the activation of T cells

A

T cell activation, proliferation and differentiation
lots of cells ready to destroy pathogen directly or indirectly

49
Q

what do effector cells not need

A

co-stimulation to exert their function

50
Q

what are the types of t helper cells

A

Th1
Th2
Th17
Tfh
T reg

51
Q

Th1

A

polarising cytokine: IL-12
transcription factor: T-bet
cytokine produced: IFN gamma
primary function: activate macrophages

52
Q

Th2

A

polarising cytokine: IL-4
transcription factor: GATA3
cytokines produced: IL4,5 and 13
primary function: activate eosinophils and mast cells, alternative macrophage function

53
Q

th17

A

polarising cytokine: IL-6 and 21
transcription factor: ROR gamma T
cytokines produced: IL-17 and 22
primary function: enhance neutrophil response

54
Q

Tfh

A

polarising cytokine: IL-6, TGF beta, IL-23
transcription factor: Bcl6
cytokines produced: IL-21 (and IL-4 or IFN gamma)
primary function: activate and mature B cells

55
Q

T reg

A

polarising cytokine: TGF beta
transcription factor: FoxP3
cytokines produced: IL-10, TGF beta
primary function: suppress other effector T cells

56
Q

what can CD8 cytotoxic T cells do after recognition

A

can kill virus infected cells

57
Q

cytotoxic T cells killing mechanism

A

killing is specific, requires the specific peptide-MHC: TCR interaction
killed by: perforin/granzyme or Fas:FasL interaction

58
Q

fas:FasL interaction

A

FasL is expressed by cytotoxic T cells and Fas is expressed by the target cells
FasL- Fas interaction activates FADD then pro-caspase 8 in the target cell
during apoptosis, caspases are activated
activation of cascades results in orderly destruction of the target cell

59
Q

what are caspases

A

cysteine proteases that cleave aspartic acid

60
Q

granzymes/ perforin

A

exocytosis of lytic granules at the immune synapse
attack of the target membrane: perforin polymerise forming cylindrical pores in the target cell, granzymes enter
triggering of caspase cascade, leading to DNA cleavage and cell death

61
Q

CD4 T cell help of CD8 T cell ctivaiton

A

activated CD4 T cells expresses CD40L ligand on its surface
induces expression of IL-2
cross primes CD8 by enhancing APC activation
stimulation of APC through CD40 increases B7 and CD40, co-stimulate naive CD8, increase APC production of IL-12

62
Q

cross presentation

A

how antigen taken up by phagocytosis gets loaded onto MHC 1
important for anti-tumour and anti-viral immunity

63
Q

b cells

A

produced in the bone marrow and exit with the recombined antigen
antigen receptor is the B cell receptor
B cells with BCR specific to the antigen become activated, proliferated and differentiate into effector cells
plasma cells make antibodies

64
Q

stages of B cell immune response

A

diversity
specific recognition
activation
proliferation and differentiation
effector cells and memory cells

65
Q

what is in the image

A

surface antibody

66
Q

what is in the image

A

soluble antibody

67
Q

rearrangement of immunoglobulin genes

A

rearrangement at heavy and light lg chain loci
nucleotides are added or removed at random between the segments as they come together in the recombined gene

68
Q

B cell receptors

A

bind directly to the antigen even if they are still attached to the pathogen

69
Q

B cell 3 signals

A

BCR signalling and uptake
co-stimulation
cytokines

70
Q

B cell first signal

A

antigen activates the B cell via the BCR
it is taken up, processed and presented on MHC 2 to a specialised CD4 t helper cell

71
Q

B cell second signal

A

CD40: CD40L

72
Q

B cell third signal

A

cytokines produced by the T cell intersect the B cell to produce certain antibody type

73
Q

B cell activation

A

B cell is activated, proliferates and differentiated into plasma cells and memory cells
IgM is the first antibody class type to be made

74
Q

what is the first antibody class type to be made

A

IgM

75
Q

plasma cells

A

produce and secrete antibody
cytokines produced by the T cell direct class-switching of B cells

76
Q

what must the classes of antibodies have

A

a different heavy chain constant region, region linked to the function

77
Q

variable region q

A

determines antigen specificity

78
Q

constant region

A

determines antibody class
finds Fc receptors

79
Q

what are the 5 types of antibodies

A

IgG
IgE
IgD
IgA
IgM

80
Q

IgG

A

multi-purpose
high affinity
crosses the placenta

81
Q

IgE

A

parasite responses and allergies

82
Q

IgD

A

basophils

83
Q

IgA

A

secreted at mucus sites

84
Q

IgM

A

first to be made on encounter with antigen

85
Q

IL-4 role of regulating expression of antibody classes

A

inhibits: IgM, IgG3 and IgG2a
induces: IgG1, IgE

86
Q

IL-5 role of regulating expression of antibody classes

A

augments production of IgA

87
Q

IFN- gamma role of regulating expression of antibody classes

A

inhibits: IgM, IgG1, IgE
induces: IgG3, IgG2a

88
Q

TGF- beta role of regulating expression of antibody classes

A

inhibits: IgM, IgG3
induces: IgG2b, IgA

89
Q

IL-21 role of regulating expression of antibody classes

A

induces: IgG3, IgG1, IgA

90
Q

what are the functions of antibodies

A

neutralisation
opsonisation
complement activation
NK cell sensitisation
mast cell, eosinophil and basophil sensitisation

91
Q

neutralisation

A

IgA and IgG
antibodies that bind bacterial toxins and virus particles
stop them binding receptors on host cells and prevent damage to tissue

92
Q

opsonisation

A

IgG
antibodies that bind to pathogens
phagocytes recognise bound antibody via Fc receptor
trigger phagocytosis and killing

93
Q

complement activation

A

IgM and IgG
antibodies that bind pathogens and activate the complement pathway
trigger formation of membrane attack complex and killing of pathogen

94
Q

NK cell sensitisation

A

IgG
antibodies binds antigens on the surface of target cells
Fc receptors on NK cells recognise bound antibody
cross-linking of Fc receptors signals the NK cell to kill the target cell
target cell dies by apoptosis

95
Q

mast cell sensitisation

A

mast cells express Fc receptors recognising IgE
crosslinking of the antibodies by antigen causes mast cell degranulation
releasing mediators such as histamine

96
Q

eosinophil sensitisation

A

regonise UgE bound to parasites and release granules to kill the parasites

97
Q

basophil sensitisation

A

recognise IgD
activating anti-microbial and pro-inflammatory mechanisms

Medicine Unit 3 (28 decks)

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