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Y1 - Infection > Lecture 4 - Innate Immunity > Flashcards

Lecture 4 - Innate Immunity Flashcards

1
Q

What is infectivity?

A

The ability for a microorganism to infect a host and therefore establish itself

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2
Q

What is virulence?

A

The ability of a microbe to drive/cause tissue damage

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3
Q

Which 3 groups of people have weak immune systems and are therefore more susceptible to infections?

A

Elderly people (65yrs +)
Children (less than 5 yrs)
Pregnant women

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4
Q

What is the definition of the immune system?

A

The cells and organs that contribute to immune defences against infectious and non-infectious conditions

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5
Q

What is an infectious disease?

A

When the pathogen succeeds in evading and/or overwhelming the hosts immune defences

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6
Q

What are the roles of the immune system?

A

Pathogen recognition
Containing/eliminating the infection
Regulating itself (ending once infection is gone)
Remembering pathogens (immunological memory)

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7
Q

What principles do vaccines use to work?

A

Modified version of microbe
Stimulates normal immune response from body
Immunological memory created (preventing illness when infected by actual pathogen)

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8
Q

What are the 2 components to the immune response?

A

Innate immunity
Adaptive immunity

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9
Q

What is the main difference between innate and adaptive immunity?

A

Innate immunity provides immediate protection
Adaptive immunity provides long lasting protection

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10
Q

What are the features of the innate immunity giving immediate protection?

A

Fast/rapid acting
Lack of specificity
Lack of memory
No change in intensity

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11
Q

What are the feature of the adaptive long lasting protection ?

A

Slow
Specific
immunological memory
Changes in intensity (due to immunological memory, faster and stronger upon repeat infection)

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12
Q

In innate immunity, what are the 4 first lines of defence?

A

Physical barriers
Physiological barriers
Chemical barriers
Biological barriers

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13
Q

What is the general function of the first lines of defences in innate immunity?

A

They prevent the entry and limit the growth of pathogens

Prevent microbes getting in

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14
Q

What are the innate physical barriers to infection?

A

Skin
Mucous membranes
Bronchial cilia

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15
Q

Where are the mucous membranes of the body located?

A

Mouth
Respiratory tract
GI tract
Urinary tract

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16
Q

What is the function of the Bronchial cilia?

A

Waft mucus that has trapped pathogens to the back of the oesophagus to be swallowed and destroyed

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17
Q

What are the physiological barriers of innate immunity?

A

Diarrhoea
Vomiting
Coughing
Sneezing

These usually happen once a pathogen has breached a physiological barrier

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18
Q

What is the general function of the physiological barriers?

A

Usually trying to expel pathogens from the body

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19
Q

What are the chemical barriers of innate immunity?

A

Low pH (skin, stomach and vagina)
Antimicrobial molecules:
-(IgA in saliva, tears and mucous membranes)
-Lysozymes
-Mucus
-Beta-defensins
-Gastric acid + pepsin

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20
Q

What are Beta-defensins?

A

Chemicals with antimicrobial properties

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21
Q

How does IgA (Immunoglobulin A) act as an antimicrobial molecule?

A

Prevent attachment to host

Antibody that binds to microbe preventing it attaching to the host

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22
Q

What is the biological barrier of the body?

A

The normal flora of the body

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23
Q

What is meant by the normal flora of the body?

A

Non pathogenic microbes that are normally present in/on the body

Can cause disease when displaced from intended site

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24
Q

Where is the normal flora of the body normally located?

A

Skin
All mucosal surfaces

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25
Q

How does the bodies normal flora act as a biological barrier to infection?

A

Competition

Competes with pathogens for attachment sites and resources
Produce antimicrobial chemicals

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26
Q

Which organ in the body deals with encapsulated bacteria?

A

Spleen

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27
Q

Where is Staphylococcus aureus normally found and what condition does it cause if it invades the body?

A

Skin
Invades subcutaneous layer causing:
CELLULITIS

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28
Q

Where is Streptococcus pyogenes normally found and what disease does it cause if it is displaced?

A

Skin
Scarlet fever

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29
Q

Where is Streptococcus mutans normally found and what disease can it cause if its displaced?

A

Mouth and nasopharynx
Endocarditis

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30
Q

Where is E.coli normally found and what disease does it cause if its displaced?

A

GI tract
Food poisoning

31
Q

How can the normal flora be displaced from its normal location?

A

Breaching the skin integrity
Fecal oral route
Fecal-perineal-urethral route (UTIs women)

32
Q

Where is the main portal of entry for microbes into the body?

A

The mouth

33
Q

When do problems with normal flora arise?

A

Normal flora displaced
Overgrowth when host is immunocompromised
Normal flora depleted due to antibiotics

34
Q

How does Chemotherpy cause problems with the normal flor?

A

Inflames the mucous membranes (mucositis) allowing normal flora to invade the host

35
Q

What are the secondary lines of defence in innate immunity that lead to Inflamation?

A

Phagocytes
Chemicals

36
Q

What is the function of the secondary line of defence of innate immunity?

A

They contain and clear the infection

37
Q

What are exogenous microbe invaders?

A

Microbes that invade that aren’t normally present in the host

38
Q

What are endogenous microbe invaders?

A

Normal flora that breach and invade

39
Q

What are phagocytes?

A

White blood cells which first respond to an infection and engulf a pathogen

40
Q

What are the 3 types of phagocyte?

A

Macrophage
Monocytes
Neutrophils

41
Q

What is a macrophage?

A

Phagocyte only found in tissues and organs

42
Q

What is the function of a macrophage?

A

Phagocytosis (ingest and destroy microbes)
Present antigens to T cells (adaptive immunity)
Make cytokines/chemokines

43
Q

What important clinical marker do cytokines cause elevated levels of?

A

cRP (c Reactive Protein)

44
Q

What are monocytes?

A

Phagocytes found in the blood
They migrate to tissues and differentiate into macrophages

45
Q

How are neutrophils different to macrophages?

A

Neutrophils =
Increased levels during infection
+ Shorter lived than macrophages

46
Q

What are the functions of basophils/mast cells?

A

Inflammation (histamines)
Allergic reactions

47
Q

What is the function of eosinophils?

A

Defence against parasites (multicellular)

48
Q

What is the function of natural killer cells?

A

Kill all abnormal host cells

49
Q

What is the function of dendritic cells?

A

Present microbial antigens to T cells (important for acquired immunity)

50
Q

How do phagocytes recognise which microbes are pathogens to be ingested?

A

PAMPs
PRRs

51
Q

Where are PAMPs located?
What does it stand for?

A

On microbes/pathogens
Pathogen Associated Molecular Patterns

52
Q

Where are PRRs located?
What does it stand for?

A

On phagocyte
Pathogen Recognition Receptors

53
Q

How do PAMPs of microbes interact with the PRRs of phagocytes?

A

The phagocytes PRRs (Pathogen Recognition Receptors) will match the PAMPs (Pathogen-associate molecular patterns) on the pathogen

54
Q

How is it useful for 1 PRR on a phagocyte to match/recognise multiple PAMPs?

A

Phagocyte can recognise and phagocytose many different pathogens

55
Q

What is opsonisation of microbes?

A

When the host coats microbes in proteins (opsonise) which a phagocyte can recognise leading to enhanced attachement to phagocytes

56
Q

What can act as opsonins?

A

Complement proteins (C3b)
Antibodies (IgM and IgG)
Acute phase proteins (C-reactive protein cRP)

57
Q

If opsonins are not present or non functional, which type of microbes cant be removed?

A

Encapsulated bacteria:
-Neisseria meningitidis
-Haemophilus influenzae
-Streptococcus pneumoniae

58
Q

How does phagocytosis take place?

A

Pathogen recognised
Pathogen binds to phagocyte
Engulfed
Phagosome
Phagolysosome
Digested

59
Q

How does a phagocyte kill a microbe once its been engulfed in a phagolysosome? (Main mechanism)

A

Respiratory burst/ Oxygen-dependant pathway

60
Q

What is involved in the chemical portion of the second line of defence of innate immunity?

A

Complement system/proteins
Cytokines

61
Q

What is the complement system?
What organ is the main contributor to producing complement?

A

Proteins in blood serum which get activated by coming into contact with invading microbes

Liver = main complement producing organ

62
Q

Which complement proteins attract phagocytes to microbes?
(Chemoattractants)

A

C3a
C5a *

63
Q

Which complement protein binds to pathogens (opsonisation)?

A

C3b

64
Q

Which complement proteins bind to surface of pathogens and kill the pathogen?

A

C5
C6
C7
C8
C9

65
Q

What is the function of cytokines?

A

Chemoattraction
Activates phagocytes
Inflammation

66
Q

What systemic affects do cytokines have ini the body?

A

Liver makes opsonins
Bone marrow mobilises neutrophils
Fever (hypothalamus increases body temp)

67
Q

How do cytokines cause local inflammation?

A

Vasodilation
Increased vascular permeability

68
Q

Innate immune response summarised:

A

Innate barrier may get breached
Complement proteins made/activated
Macrophages/phagocytes activated
Cytokines made
Vasodilation/vascular permeability
Chemoattraction
Fever
Inflammation

69
Q

When may phagocytosis be reduced causing problems?

A

Asplenic/Hyposplenic patients
Neutropenia (chemotherapy, leukaemia, certain drugs)
Decreased neutrophil function (Chronic Granulomatous Disease caused by NAPDH oxidase defect)

70
Q

Give 2 conditions where neutrophils have decreased function:

A

Chronic granulomatous disease (no respiratory burst) due to phagocyte NADPH oxidase deficiency
Chediak-Higashi syndrome (No phagolysosome formation)

71
Q

First line defences and second line defences of innate immunity purpose:

A

First line = limit entry and growth of pathogens at portals of entry

Second line = contain and eliminate infection

72
Q

What specific cytokines produced by macrophages stimulate the liver to produce CRP?

A

IL-1
IL-6
TNF-a (Tumour Necrosis Factor - Alpha))

73
Q

What is the function of cRP?
What stimulates its production?

A

Opsonisation

Macrophages producing the cytokines IL-1, IL-6 and TNF-a

74
Q

What cells produce IL-1, IL-6 and TNF-a?
What do these cytokines do?

A

Macrophages produce them
These cytokines are pyrogens inducing fever

Y1 - Infection (21 decks)

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