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Microorganisms + Disease > Adaptive Immunity in action L10 > Flashcards

Adaptive Immunity in action L10 Flashcards

(65 cards)

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1
Q

what do B cells make

A

antibodies

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2
Q

what do T cells make

A

CD4 helper T cells and CD8 cytotoxic T cells

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3
Q

what do T helper cells do

A

activate B cells

provide signals eg cytokines which can activate other immune cells, for example phagocytosis by macrophages

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4
Q

what do regulatory T cells do

A

suppress activity of other lymphocytes , to try and limit the damage caused by immune response

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5
Q

how are B and T cell receptors compared

A

Antibodies have light chain heavy chain

T cells alpha chain and beta chain

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6
Q

what do all nucleated cells have

A

MHC class I

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7
Q

what do only antigen presenting cells have

A

MHC class II

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8
Q

when can T cells recognise peptides

A

only recognise peptides when presented in a MHC molecule

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9
Q

what must primarily match in an organ transplant

A

primarily the MHC type that needs matching

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10
Q

what is somatic recombination

A

rearrangement of gene segments to give huge diversity in variable regions

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11
Q

what is the clonal selection theory

A

a single progenitor cell gives rise to large number of lymphocytes, each with different specificity
removal of potentially self-reactive immature lymphocytes by clonal deletion
pool of mature naive lymphocytes
proliferation and differentiation of activated specific lymphocytes to form a clone of effector cells

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12
Q

what are the postulates of clonal selection hypothesis

A
  • each lymphocyte bears a single type of receptor with a unique specificity
  • interaction between foreign molecule and lymphocyte receptor capable of binding that molecule with high affinity leads to lymphocyte activation
  • differentiated effector cells derived from an activated lymphocyte will have receptors of identical specificity to parental cell lymphocyte is derived from
  • lymphocytes with receptors specific for always present self molecules are deleted at each early stage in lymphoid cell development and are absent from repertoire of mature lymphocytes
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13
Q

what is the innate immune system response

A

inflammation
complement activation
phagocytosis
destruction of pathogen

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14
Q

how long after infection till innate immune response starts

A

minutes

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15
Q

how long does the innate immune response last

A

days

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16
Q

what is the adaptive immune response

A

interaction between antigen-presenting dendritic cells and antigen-specific T cells
antigen-specific B cells activated
memory T cells and effector form
T cell and B cell interaction
emigration of effector lymphocytes from peripheral lymphoid organs
elimination of pathogen by effector cells and antibody

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17
Q

what happens when there is is an interaction between antigen-presenting dendritic cells and antigen-specific T cells in adaptive immune response

A 
recognition of antigen
adhesion
co-stimulation
T-cell proliferation
differentiation
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18
Q

what happens when there is T cell and B cell interaction in adaptive immune response

A

formation of germinal centres
formation of effector B cells (plasma cells) and memory B cells
produce antibody

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19
Q

which parts of adaptive immune response take hours after infection

A

interaction between antigen-presenting dendritic cells and antigen-specific T cells
antigen-specific B cells activated

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20
Q

which parts of the adaptive immune response take days after infection

A

memory T cells and effector form

T cell and B cell interaction - antibodies produced

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21
Q

which parts of the adaptive immune response take a few days after infection

A

emigration of effector lymphocytes from peripheral lymphoid organs
elimination of pathogen by effector cells and antibody

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22
Q

which parts of the adaptive immune response last only days

A

interaction between antigen-presenting dendritic cells and antigen-specific T cells
antigen-specific B cells activated

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23
Q

which parts of the adaptive immune response last weeks

A

memory T cells and effector form
T cell and B cell interaction
emigration of effector lymphocytes from peripheral lymphoid organs
elimination of pathogen by effector cells and antibody

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24
Q

what is the immunological memory

A

maintenance of memory B cells and T cells and high serum or mucosal antibody levels
protection against reinforcement

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25
how long does immunological memory response take after infection
days to weeks
26
how long does immunological memory last
can be life
27
what is the crucial role of dendritic cells
act as a crucial link between innate and adaptive immune systems activating the adaptive immune response
28
what can dentritic cells do
“talk” to lymphocytes
29
where are immature dendritic cells
peripheral tissues
30
where do dendritic cells migrate
via lymphatic vessels to regional lymph nodes
31
where do mature dendritic cells activate molecules, and what
mature dendritic cells activate naive T cells in lymphoid organs e.g. lymph nodes
32
what is the CD4 positive cell for
is a helper cell
33
what is the antigen presented to
CD4 positive T
34
how are CD4 positive proteins identified
protein called CD4 on their surface, a co-receptor which is required to enable interaction between their T cell receptor and MHC class II
35
what dies the dendritic cell do to help activate T cells
produce soluble signals
36
how does an activated T cell recognise B cell
activated helper T cell can recognise B cells that have a B cell receptor (surface-antibody) which has bound the same pathogen molecules and are presenting the same peptide
37
how does the T cell activate the B cell
by both direct cell-to-cell interactions and soluble signals (cytokines)
38
what does the activated B cell do
will then proliferate and price plasma cells which make large quantities of the specific antibody
39
how do antibodies improve during infection
antibody affinity improves over an immune response
40
what are plasma cells
terminally differentiated activated B cells | main antibody secreting cells of body
41
what can dendritic cells, macrophages and B cells be called
antigen presenting cells | APC
42
how are dendritic cells specialised
specialised in initiating adaptive immune response§
43
how are dendritic cells activated, effect
PAMPS binding to PRR’s stimulate dendritic cells to engulf pathogen and degrade it intracellularly (phagocytosis) Can also take up virus particles and bacteria through receptor-independent macropinocytosis
44
what mainly causes B cell activation
main cause: interaction with CD4 T helper cells | also, can be due to binding of free antigens
45
what does B cell activation cause
optimal antibody response
46
how are B cells activated by binding of free antigens
antigen-specific B cell binds antigen specific antigen is efficiently internalised by receptor mediated endocytosis high density of specific antigen fragments are presented at B-cell surface
47
what are the effects of pathogen specific antibodies
Neutralize toxins Block virus binding to cells Opsonise pathogens Activate complement All aid in removal of pathogens
48
what is Fc
Fragment crystallisable (Fc), it’s a portion of the antibody in the constant domain
49
what happens in toxin neutralisation by antibodies
toxin binds to cell surface receptor endocytosis of toxin:receptor complex dissociation of toxin to release active chain which poisons cell neutralising antibody blocks binding of toxin to cell-surface receptor
50
what happens in pathogen oponisation (tagging) by antibodies
antibody binds to bacterium antibody-coated bacterium binds to Fc receptors on cell surface macrophage membrane surrounds bacterium macrophage membranes fuse, creating a membrane-enclosed vesicle, phagosome lysosomes fuse with phagosome, creating phagolysosome
51
what is antibody dependent cell-mediated cytotoxicity used in
Can be used as a therapy – anti-CD20 monoclonal antibody eliminates some types of B cell tumors (rituximab)
52
what happens in antibody dependent cell-mediated cytotoxicity
The monoclonal IgG antibody binds to cell surface protein CD20, and the Fc receptors on the NK cells can recognise this and lead to cell apoptosis
53
how are viruses neutralised
virus binds to receptors on cell surface receptor-mediated endocytosis of virus acidification of endosome after endocytosis triggers virus and cell fuse and entry of viral DNA antibody blocks binding to virus receptor and can block fusion event
54
how are viruses replicated
To replicate viruses have to get genes into host cell
55
how is bacteria neutralised
colonisation of cell surface by bacteria that bind to surface via bacterial adhesin some bacteria become internalised and propagate in internal vesicles antibodies against adhesins block colonisation
56
what are the T cell effector functions (CD8+ cytotoxic T cell)
cytotoxic T cell recognises complex of viral peptide with MHC class I kills infected cell
57
what are the T cell effector functions (CD4+ T helper cell)
``` Th1 cell recognises complex of bacterial peptide with MHC class II, activates macrophage T follicular helper cell recognises complex of antigenic peptide with MHC class II and activates B cell = antibodies ```
58
how does CD8+ kill target cells
CD8 cells kill target cells by releasing the content of intracellular granules at the site of cell contact CD8 T cells can kill cells bearing a specific antigen, whilst sparing neighbouring cells
59
what granules does CD8+ T cells contain
perforin granzymes granulysin
60
what does perforin do
aids in delivering contents of granules into cytoplasm of target cells
61
what does granzymes do
serine proteases, which activate apoptosis once in cytoplasm of target cell
62
what does granulysin do
has antimicrobial action, can induce apoptosis
63
where are naive T cells
circulate though the blood and lymphoid organs
64
when are T cells activated
after encountering antigen presenting cells showing a peptide/MHC complex
65
what do activated T cells do
proliferate in the secondary lymphoid organs (lymph nodes, spleen etc) and two key sorts are produced: most become effector T cells which are actively involved in the immune response, a lesser proportion become long-lived memory T cells

Microorganisms + Disease (16 decks)

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