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Microorganisms + Disease > Cells of the innate immune system L5 > Flashcards

Cells of the innate immune system L5 Flashcards

1
Q

what are the two types of immune responses

A

innate immunity

adaptive immunity

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2
Q

what is innate immunity

A

fast response, but is fixed, wont adapt overtime not always enough to clear it – so have adaptive

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3
Q

what is adaptive immunity

A

adapt to pathogen – takes longer about 3 days to adapt

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4
Q

what cells are involved in innate immunity

A 
macrophage
dendritic 
neutrophil
eosinophil
basophil
natural killer
mast
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5
Q

what are general characteristics of macrophages and dendritic cells

A
  1. High endocytic and phagocytic capacity
  2. Sense and respond to environment
  3. Wide range of killing mechanisms
  4. Link between innate and adaptive immune systems§
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6
Q

what is enodcytosis

A

method of taking up soluble compounds, or particulate matter

Engulf in the outside material – soluble components

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7
Q

when is phagocytosis initiated

A

when certain receptors on the surface of the cell (usually macrophage, neutrophil or dendritic cell) interacts with the microbial surface

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8
Q

other than phagocytosis how else can pathogens be taken up

A

macropinocytosis, in which large amounts of extracellular fluid and its contents are ingested

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9
Q

how does a phagolysosome from

A

As endosome matures becomes more acidic to form lysosome

Lysosome joins with phagosome to form phagolysosome

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10
Q

what can phagolysosomes cause

A

degradation of bacteria (some can survive this)

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11
Q

how can macrophages recognise material

A

through:

  • opsonic (indirect recognition)
  • non-opsonic (direct recognition) receptors
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12
Q

examples of indirect receptors

A

antibody-Fc receptor (FcR)

complement-complement receptor

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13
Q

what is the Fc portion

A

constant region of the antibody

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14
Q

what are PRRs

A

pattern recognition receptors

on receptor surface of all cell types

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15
Q

what are PAMPs

A

pathogen associated molecular patterns

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16
Q

what is the specificity receptors in adaptive immunity

A

one cell only have one specificity of receptor

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17
Q

how do phagocytes bind to macrophages

A

macrophages have phagocytic receptors that bind microbes and their components

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18
Q

how can phagocytes bind to many different things

A

they have many receptors on their surface

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19
Q

where are PRRs present

A

cell surface as well as in endosomes and cytosol

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20
Q

what is germ-line

A

receptors are in our DNA so don’t change

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21
Q

how do PAMPs detect pathogens

A

PAMPs detecting patterns that are more associated with pathogens than commensals
Immediate response – immune response within hours to detect and kill pathogens

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22
Q

how do the pattern recognition receptors attach to the pathogens

A

Coated in LPS lipid polysaccharide
receptors can bind to LPS interacts and macrophage can detect the pathogen
So much microbiome - need to know bacteria is good for you (commensal or pathogenic)

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23
Q

how does the gram negative bacteria interact with the plasma membrane

A

Gram negative coated in LPS bind to LPS binding protein binds to the CD14 which then reacts to the TLR4, these can form complexes that can be recognised by the pathogen

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24
Q

how does the gram positive bacteria interact with the plasma membrane

A

Gram positive don’t have LPS so look for different glycoproteins on surface e.g.fungi
Use TLR1 and TLR2 or TL2 and TLR6

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25
Q

how can bacteria with flagellum use this for innate immunity

A

TLR5 bind to flagellum and helps phagocytosis – innate immunity to detect different things

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26
Q

where are toll like receptors

A

plasma membrane and endosomes

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27
Q

what happens when macrophages and dendritic cells encounter PRRs

A

Macrophages and dendritic cells respond to PRR engagement by producing cytokines

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28
Q

what size are cytokines

A

Cytokines are small (~25 kDa)

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29
Q

what are cytokines involved in

A

Involved in cell-cell communication

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30
Q

what does tumour necrosis factor alpha so

A

activates vascular endothelium and increases vascular permeability

31
Q

what does interleukin - 1 beta do

A

Activates vascular endothelium and activates lymphocytes

32
Q

what does interleukin - 6 do

A

Lymphocyte activation, increased antibody production

33
Q

what does interleukin - 12 do

A

Activates NK cells, induces differentiation of CD4 T cells into TH1 cells

34
Q

what are killing mechanism examples

A 
acidification
toxic oxygen-derived products
toxic nitrogen oxides
antimicrobial peptides
enzymes
competitors
35
Q

what does acidification mechanism produce

A

pH `3.5-4

bacteriostatic/bactericidal

36
Q

what does toxic oxygen-derived products mechanisms produce

A 
super oxide O2-
hydrogen peroxide H2O2
singlet oxygen 1O2*
hydroxyl radical OH*
hypohalite OCl-
37
Q

what does toxic nitrogen oxides mechanisms produce

A

nitric oxide

38
Q

what does antimicrobial peptides mechanisms produce

A

defensins

cationic proteins

39
Q

what does enzymes mechanisms produce

A

lysozyme - dissolves cell walls of walls of Gram-positive bacteria
acid hydrolases - further digest bacteria

40
Q

what does competitors mechanisms produce

A

lactoferrin (binds Fe)

vitamin B12-binding protein

41
Q

what are the microbicidal activity of phagocytes

A

Toxic species damage bacterial proteins and DNA
Iron pump to remove iron from phagosome
Antimicrobial peptides
Make phagosomes as inhospitable as possible

42
Q

what happen to dendritic cells are infected

A

mature

43
Q

what are the characteristics of immature dendritic cells

A 
High endocytic activity
Intracellular MHC class II
Constantly sampling the environment
44
Q

what are the characteristics of mature dendritic cells

A 
Low endocytic activity
High surface expression of MHC class II
Once activated produce cytokines
Migrate to lymph nodes
Stop sampling and display MHC class II on surface
45
Q

what do dendritic cells do

A

Present fragments on surface for antigen presentation for T cell

46
Q

what is phagocytosis enhanced by

A

engagement of receptors

47
Q

how is a phagolysosome formed

A 
endosome 
early (less acidic) goes to late (more acidic) 
lysosome (very acidic)
joins with the phagosome 
form phagolysosome
48
Q

what is dendritic communication

A

Dendritic cells can “talk” to lymphocytes

49
Q

when can T cells recognise peptides

A

T cells can only recognise peptides when presented by Major Histocompatability Complex

50
Q

what are the two types of Major Histocompatability Complex

A 
class I
class II
51
Q

what do all nucleated cells have

A

Major Histocompatability Complex I

52
Q

what Major Histocompatability Complex do antigens have

A

class II

53
Q

how do MHC class I interact with T cells

A

CD8 T cells (killer T cells) Present endogenous peptides

54
Q

how do MHC class II interact with T cells

A

CD4 T cells (helper T cells)

Present peptides formed from exogenous peptides

55
Q

where are mast cells predominantly

A

Mainly reside near small blood vessels in a wide variety of tissues

56
Q

what do mast cells do

A

Release substances that alter vascular permeability such as histamine

57
Q

what happens when mast cells binds to C3a and C5a

A

Binding to C3a and C5a induces degranulation and release of granule contents

58
Q

what do mast cells release

A

histamine

59
Q

what are the products of mast cell - preformed mediators

A

histamine
heparin
proteases
chondroitin sulphate

60
Q

what do mast cells do

A 
recruitment and activation of immune cells
phagocytosis and antimicrobial activity
tissue repair 
vascular permeability 
toxin degradation
61
Q

what are the products of the mast cells after histamine is released

A

blood clots
frequent heartbeat
adrenaline released

blood vessels to dilate
bronchoconstriction 
increases capillary permeability
swelling and inflammation
gastric acid secretion
62
Q

what are natural killer cells

A

large lymphocytes that circulate in blood

63
Q

what do natural killer cells do

A

Provide innate immunity against intracellular pathogens and migrate from the blood into infected tissues in response to inflammatory cytokines

64
Q

what happens to patients that lack natural killer cells

A

suffer from persistent viral infection which they can not clear without the help of antiviral drugs

65
Q

what are the two types of effector function for natural killer cella

A

cell killing

secretion of cytokines

66
Q

how do natural cells recognise their targets

A

NK cells express combinations of receptors specific for surface molecules

67
Q

what do natural killers do when they bind to ligands

A

some of these receptors inhibit killing activity while others stimulate killer function

68
Q

how are natural killer cells balanced

A

balance between inhibitory and stimulatory signals that determines whether a potential target is killed

69
Q

what happens when the normal cell has +ve and -ve receptor - natural killer cells response

A

no killing

70
Q

what happens when the abnormal cell has one +ve receptor - natural killer cells response

A

killing

clear infection

71
Q

what happens when the abnormal cell has two +ve and -ve receptor - natural killer cells response

A

too much activation so not enough inhibition = killing

clear viral infection

72
Q

what happens in the absence of MHC class 1 in cells

A

it activates killing as there is no longer a suppression of the receptor

73
Q

how do natural killer cells kill

A

release lytic granules that kill some virus-infected cells

Microorganisms + Disease (16 decks)

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