MP324 > Immune system > Flashcards

Immune system Flashcards

(57 cards)

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1
Q

what is the innate immune system?

A
  • early phase of the host response
  • present in all individuals at all times
  • does not increase with repeated exposure
  • discriminates between groups of pathogens
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2
Q

what is the role of the innate immune system?

A

to make initial recognition/ defence against pathogens and also helps acitivate the adaptive immune reponse when it fails

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3
Q

what does the innate immune system involve?

A

early responding cells: neutrophils, macrophages, eosinophils, dendritic cells

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4
Q

what is the adaptive immune system?

A
  • generated by specific lymphocytes
  • discriminates between individual pathogens
  • is associated with memory
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5
Q

what is activated in the adaptive immune system by dentritic cells?

A

T and B cells

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6
Q

how low does it take the innate immune system to kick in?

A

minutes to hours

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7
Q

how long does it take for the adaptive immune system to kick in?

A

1-4 days

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8
Q

what are anatomical barriers?

A

skin
oral mucosa
respiratory epithelium
intestine

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9
Q

what do lyszymes do?

A

digest bacterial cell walls

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10
Q

what is an example of an antimicrobial peptide?

A

defensins

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11
Q

what are lectins?

A

binds to bacterial cells and kills then eg. RegIII

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12
Q

what do receptors of different cell type epithelial cells recoognise ad respond to?

A

bits/fragments of the pathogen (pathogen associated molecular patterns)

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13
Q

what do toll like receptors sense?

A

gram -ve and gram +ve bacterua , viruses and flagella proteins

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14
Q

How do TLRs respond to viruses ?

A

inside the cells responding to double and single stranded RNA

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15
Q

what is really important to sense pathogens (mostly bacteria) getting into the cell?

A

NODS

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16
Q

what are short term mediators of inflammation?

A

prostaglandins, leukotrienes, bradykinin

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17
Q

what are chemokines?

A

small molecules which attract white blood cels to area of infection (short and long)

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18
Q

what are cytokines

A

longer
large proteins which activate innate immune cells to make inflammatory and immune proteins via trascription
- also important in shaping the immune responses of T cells

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19
Q

what is the process of inflammation in presponse to a pathogen

A
  • release of cytokines and chemokines from epithelial cells, endothelial cells, neutrophils, macrophages
  • increased blood flow and endothelial leakiness and diapedesis
  • increased neutrophils and macrophafes to site of infection
  • neutrophils and macrophages release chemicals to kill pathogen and engulf
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20
Q

what are the different types of T cells?

A

CD4+ - helper (helps activate effector cells)
CD8+ -killer cells that differentiate to cytotoxic cells

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21
Q

what do B cells make

A

antibodies to recognise and bind to pathogen and tags the pathogen for destruction by neutrophils and macrophages

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22
Q

what does dendritic cells do to activate T-cells?

A
  • take up the pathogen, cut it up and digest
  • peptude present to naive CD4+ cell via MHCII protein
  • CD4+ T-cell receptor then recognises the peptide as foreign and activates T cell
  • naive CD4+ then proliferates and differentiates to produce chemokines and cytokines to recognise/fight the pathogen
  • naive CD8+ T cells get activated via a similar way via MHCI to become cytotoxic T cells which directly recognise the pathogen and kill it
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23
Q

how is naive t cell activated

Study These Flashcards
A
  • pertide is presented to T cell, need co-stimulation of additional receptors called co-receptors (if not T cell will go into hyporesponsive state and die)
24
Q

what else can present to T cells

25
what are the 3 ways to activate the adaptive immune system?
- t cell activation - co-receptor activator from dendritic cell - cytokines from dentritic cell or elsewhere to further stimulate
26
where does activation of T cells occur
lymph nodes
27
what else does dendritic cells do?
by being activated by cytokines and slo by pathogens directly via TLRs - it knows what type of pathogen it is, so releases its own cytokines to direct the naive CD4+ down a certain lineage
28
what lineage does CD4+ differentiate into for bacteria?
Th1 (via iL-12)
29
What lineage does CD4+ differentiate into for worm infections?
Th2 (via IL-4)
30
What are the different cells included in Th1?
interferon gamma (IFNy), TNFa, macrophages, neutrophiles
31
what differnt interleukins and cells are included in TH2?
IL-4, IL-5, mast cells and eosinophils
32
what is th-1 important in?
autoimmune disease
33
what does the killing in TH1?
macrophages and neutrophils (not the T cells)
34
what does eosinophils do in Th2 lineage?
releases dodgy chmeicals to kill it (worm is too big to engulf)
35
what is a naive B cell
hasnt seen pathogrn before so doesnt know how to respond - response needs to be adaptive
36
what is the B cell receptor?
antibody on the surface called IgM
37
what are memory B cells?
interact with pathogens to respond quicker the next time they are infected by a pathgen
38
what do B cells need to maximise antibody production
CD4+ helper T cells (have also seen the pathogen)
39
how do antibodies work?
- neutralising the pathogen - coating it (opsonisation) so macrophage can engulf - binding to surface and activated complement pathway - binding to nk cells which activates them to kill bacteria
40
how do macrophages help clesr pathogens in the lungs?
cells at the bottom of lungd produce surfactant which csn be type 1 respiratory cells (very thin) so pathogens dont have very much to penetrate
41
what do we want in the lungs in terms of infection??
- fight the infection to get rid of pathogen - ensure the immune response/ inflammation dies away - fix the damaged tissues/cells - physiological function restored
42
how can infection in the lungs go wrong?
- cant get rid of pathogen - immune system would stay activated and get chronic inflammation and destruction of the lungs - damaging lungs ourselves (smoking, inhaling irritants) - immune system responds when it shouldnt - asthma - chronic inflammation and tissue destruction
43
what might someone respond to in allergic asthma?
pollen, dust mite poo proteins (derp1)
44
what is the sensitisation phase of allergic asthma?
- pollen gets into tissue (engulfed by dendritic cell) - dentritic cell presents it to naive CD4+ T cell in lymph node - normally T cell wouldnt respond - but it does - T cell receptor gets activated and differentiates to TH2 with the help of IL-4 which stimulates B cells activation - B-cell makes lots and lots of antibody IgE that is sensitised to pollent - IgE binds to IgE receptors on mast cells in the lungs
45
what happens when when person is exposed to pollen again?
expresses FceRI so interacts with IgE which is bound to the receptor so pollen helps link these receptors together called cross linking which activates the mast cells and causes degranulation
46
what happens when the cells degranulate?
they release histamine and inflammatory mediators (from mast cells)
47
what happens to smooth muscle in the airways when sensitive to pollen?
smooth muscle is stimulated to contract, stimulates vagal nerve and releases Ach to cause constriction creating an inflammatory environment (more leakiness)
48
what is the second phase of allergic asthma?
Th2 cells release IL-5 and IL-13 and drives recruitment and activation of eosinophils. release of contractile mediators and destructive enzymes - damaging the epithelium
49
how do mast cells work?
- fights bacteria and parasitic infections - mast cells can infiltrate the bronchial the bronchial smooth muscle layer and contribute to bronical hyper-responsiveness
50
why are anti-histamines not effective in allergic asthma?
constriction of the airways is not caused by histamine
51
how do eosinophils work in allergic asthma?
- IL-5 supports development of eosinophils in bone marrow and recruitment into circulation - recruitment in the lungs is supported by chemokines - cytokines and leukotrienes amplify inflammatory response - eosinophil peroxidase causes broncial hyper-reactivity and activation of DCs to drive Th2 polarisation
52
what asthma might not be Th2 mediated response?
late onset or severe (can direct CD4+ T cell response to differntiate down a TH1 lineage)
53
which interlukine induces TH1?
IL12 (from dendritic cells); produce IFNy and TNF - stimualtes neutrophils and macrophages
54
what does TH1 play a cruical role in?
- protectiton against mycobacteria eg. TB - involved in protection against certain extracellular bacteria such as klebsiella pneumoniae - also involved in protextion against respiratory viruses and fungi
55
how do neutrophils work in Th1?
- destructive cells release destructive chemicals and enxymes and engulf pathogens tagged for destruction (opsonisation)
56
what is prominent disease with absense of Th2 cytokines?
have neutrophils and not eosinophils - usually more severe with increased airway remodelling and is also late onset and assoicated with steroid resistance
57
what is TH17 more important in?
COPD (may be involved in asthma but not clear)
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