Innate Immune System Flashcards Preview

[ ESA 3- Infection and Immunity > Innate Immune System > Flashcards

Flashcards in Innate Immune System Deck (127):
1

What is the immune system?

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

2

What is an infectious disease?

When the pathogen succeds in evading and/or overwhelming the host's immune defences

3

What are the roles of the immune response?

Pathogen recognition
Containing/eliminating the infection
Regulating itself
Remembering pathogens

4

What is required for the immune response to recognise pathogens?

Cell surface and soluble receptors

5

What is the purpose of pathogen recognition?

Distinguish between infectious and noninfectious diseases

6

How does the immune system contain/eliminate infection?

Killing and clearance mechanisms

7

Why is it important that the immune system regulates itself?

To produce minimum damage to the host, leading to resolution

8

Why does the immune system remember pathogens?

Prevents the disease for reoccurring

9

What are the features of the innate immune system?

Fast
Lack of specificity
Lack of memory
No change in intensity of response to primary or secondary encounters

10

How fast does the innate immune system act?

Within seconds

11

How specific is the innate immune system?

At best it can recognise groups of bacteria

12

What does the first line of immune defence consist of?

Barriers that limit entry and growth of pathogens at portals of entry

13

What are the barriers in the first line immune defence?

Physical barriers
Physiological barriers
Chemical barriers
Normal flora

14

What are the physical barriers in the innate immune system?

Skin
Mucous membranes
Bronchial cilia

15

What is the surface area of the skin?

1-2m squared

16

What do mucous membranes line?

Cavities exposed to air;
Mouth
Respiratory tract
GI tract
Urinary tract

17

What is the purpose of bronchial cilia?

Waft trapped microbes to the pharynx for swallowing

18

What are the physiological barriers in the innate immune system?

Diarrhoea
Vomiting
Coughing
Sneezing

19

When is diarrhoea a physiological barrier?

In food poisioning

20

When is vomiting a physiological barrier?

Food poisioning
Hepatitis
Meningitis

21

When is coughing a physiological barrier?

Pneumonia

22

When is sneezing a physiological barrier?

Sinusitis

23

What are the chemical barriers to infection?

Low pH
Antimicrobial molecules

24

Where has low pH to resist infection?

Skin
Stomach
Vagina

25

What pH is the skin?

5.5

26

What pH is the stomach?

1-3

27

What pH is the vagina?

4.4

28

What causes the low pH of the vagina?

Lactobacillus commensal bacteria

29

What antimicrobials molecules consist the innate immune system?

IgA
Lysozyme
Mucus
Beta-defensins
Gastric acid and pepsin

30

Where is IgA found?

Tears
Saliva
Mucous membranes

31

Where is lysozyme found?

Sebum
Respiration
Urine

32

Where is mucus found?

Mucous membrane

33

What secretes beta-defensins?

Mucous membrane epithelia

34

What is the normal flora?

Non pathogenic microbes that are found in strategic locations

35

Where are the normal flora found?

Nasopharynx
Mouth/throat
Skin
GI tract
Vagina

36

Where is normal flora absent?

Internal organs/tissues

37

What are the benefits of the normal flora?

Compete with pathogens for attachment sites and resources
Produce antimicrobial chemicals
Synthesise vitamins

38

What vitamins are synthesised by the normal flora?

K
B12
Other B vitamins

39

What organisms are found in the normal flora of the skin?

Staphylococcus aureus
Staphylococcus epidermidis
Streptococcus pyogenes
Candida albicans
Clostridium perfringens

40

What organisms are found in the normal flora of the nasopharynx?

Streptococcus pneumoniae
Neisseria meningitidis
Haemophilus species

41

When can problems occur with the normal flora?

When normal flora is displaced from its normal location to a sterile location

42

How can normal flora be displaced from its normal location to a sterile location?

Breaching the skin integrity
Poor dental hygiene/dental work
Fecal-oral route
Fecal-perineal-urethral route

43

How can the skin integrity be breached?

Skin loss (burns)
Surgery
Injection drug uses
IV lines

44

What can poor dental hygiene and dental work lead to?

Bacteraemia

45

Give three examples of poor dental hygiene or dental work that can lead to bacteraemia

Dental extraction
Gingivitis
Brushing/flossing

46

What patients are at particular risk of dental related bacteraemia?

Asplenic/hyposplenic
Damaged or prosthetic heart valves
Previous infective endocarditis

47

When is the fecal-oral route likely?

In foodbourne infection

48

When is the fecal-perineal-urethral route likely?

Urinary tract infections in women

49

When may the normal flora become overgrown and pathogenic?

When the host becomes immunocompromised
When normal flora is depleted by antibiotics

50

What may cause a patient to be immunocompromised?

Diabetes
AIDS
Malignant disease
Chemotherapy

51

What can happen in the intestines when the normal flora is depleted by antibiotics?

Severe colitis resulting from clostridium difficile

52

What can happen in the vagina when the normal flora is depleted by antibiotics?

Thrush resulting from candida albicans

53

What is the second line of defence of the innate immune system?

Phagocytes and chemicals that cause inflammation to contain and clear the infection

54

What cells are involved in innate immunity?

Macrophages
Monocytes
Neutrophils
Basophils / mast cells
Eosinophils
Natural Killer cells
Dendritic cells

55

What kind of cells are macrophages, monocytes, and neutrophils?

Macrophages

56

What organs are macrophages present in?

All organs

57

What do macrophages do?

Ingest and destroy microbes in phagocytosis
Ingest microbial antigens to T cells in adaptive immunity
Produce cytokines/chemokines

58

Where are monocytes present?

Blood

59

What % of the blood are monocytes?

5-7%

60

What do monocytes do?

Recruited to infection site and differentiated into macrophages

61

Where are neutrophils present?

In the blood

62

What % of blood leukocytes are neutrophils?

60%

63

What happens to neutrophil numbers during infection?

Increased

64

What recruits neutrophils to the site of infection?

Chemokines

65

What do neutrophils do?

Ingest and destroy pyogenic bacteria

66

Give two examples of pyogenic bacteria

S. aureus
Strep. pyogenes

67

What is the role of basophils/mast cells?

Early actors of inflammation (vasomodulation)

68

Where are basophils/mast cells important?

In allergic responses

69

When are eosinophils important?

Defence against multi-cellular parasites (worms)

70

What do NK cells do?

Kill all abnormal host cells (virus infected or malignant)

71

What do dendritic cells do?

Present microbial antigens to T cells in acquired immunity

72

How does pathogen recognition occur?

Through interactions between pathogen-associated molecular patterns (PAMPs) on the microbe and pathogen recognition receptors (PRRs) known as toll like receptors

73

What are the PAMPS for gram negative bacteria?

Lipopolysaccharides (LPS)
Lipoproteins and lipopeptides
Porin

74

What is the PRR for lipopolysaccharides?

TLR4

75

What is the PRR for lipoproteins and lipopeptides?

TLR2

76

What is the PRR for porins?

TLR2

77

What are the PAMPs for gram +ve bacteria?

Peptidoglycan
Lipoteichoic acids

78

What is the PRR for peptidoglycan?

TLR2

79

What is the PRR for lipoteichonic acids?

TLR4

80

What are the PAMPs for all mycobacteria?

Lipoarabinomannan
Mannose-rich glycans

81

What is the PRR for lipoarabinomannan?

TLR2

82

What is the PRR for mannose-rich glycans?

TLR2

83

What is the PAMP for bacterial flagella?

Flagellin

84

What is the PRR for flagellin?

TLR5

85

What are opsonins?

Coating proteins

86

What do opsonins do?

Bind to microbial surfaces

87

What does the binding of opsonins lead to?

Enhanced attachment of phagocytes and clearance of phagocytes

88

What are the classes of opsonins?

Complement proteins
Antibodies
Acute phase proteins

89

Give 2 complement proteins that can act as opsonins

C3b
C4b

90

Give two antibodies that can act as opsonins

IgG
IgM

91

Give two acute phase proteins that can act as opsonins

C-reactive protein (CRP)
Mannose-binding lectin (MBL)

92

What is opsonisation essential for?

Clearing encapsulated bacteria

93

Give an example of an encapsulated bacteria

Neisseria meningitidis

94

What do opsonins and PRRs work together to do?

Initiate phagocytosis

95

What happens once a microbe has been recognised by receptors on the surface of the phagocyte?

The microbe is engulfed and destroyed

96

What happens in the process of phagocytosis?

1. Chemotaxis and adherence of microbe to phagocyte
2. Ingestion of microbe by phagocyte
3. Formation of a phagosome
4. Fusion of the phagosome with a lysosome to form a phagolysosome
5. Digestion of ingested microbe by enzymes
6. Formation of a residual body containing indigestible material
7. Discharge of waste material

97

How do phagocytes kill pathogens?

Using different intracellular killing mechanisms

98

What intracellular killing mechanisms are used by phagocytes?

Oxygen-dependant pathway (respiratory burst)
Oxygen independent pathways

99

What happens in the oxygen-dependant pathway of phagocytic killing?

Releases toxic O2 products to kill the pathogens

100

What toxic O2 products are released in the respiratory burst?

Hydrogen peroxide
Hydroxyl radical
Nitric oxide
Singlet oxygen
Hypophalite

101

What are the oxygen-independent pathways of phagocytic killing?

Lysozyme
Lactoferrin or transferrin
Cationic proteins
Proteolytic and hydrolytic enzymes

102

Give an example of a cationic protein

Cathepsin

103

What does the complement system consist of?

20 serum proteins

104

What are the most important serum proteins in the complement system?

C1-9

105

What does C3a and C5a do?

Recruit phagocytes

106

What does C3b-C4b do?

Opsonise pathogens

107

What does C5-C9 do?

Kill pathogens by membrane attack complex

108

What are the activating pathways of the complement system?

Alternative pathway
MBL pathway

109

What happens in the alternative pathway of complement activation?

Complement initiated by cell surface microbial constituents

110

What happens in the MBL pathway of complement activation?

Complement initiated when MBL binds to mannose containing residues of proteins found on many microbes

111

Give a microbe that will induce the alternative pathway of complement activation

Endotoxins on E. Coli

112

Give two microbes that will induce the MBL pathway of complement activation

Salmonella spp.
Candida albicans

113

What to cytokine/chemokines cause?

Chemoattraction
Phagocyte activation
Inflammation

114

Give three chemokines

TNF-alpha
IL-1
IL-6

115

Where do TNF-alpha, IL-1, and IL-6 have effects?

Liver
Bone marrow
Hypothalamus
Also have inflammatory actions

116

What is the effect of chemokines in the liver?

Release CRP
Release MBL, leading to complement activation

117

What is the effect of chemokines in the bone marrow?

Neutrophil mobilisation

118

What is the inflammatory effect of chemokines?

Vasodilation
Vascular permeability
Adhesion molecules lead to attraction of neutrophils

119

What is the effect of chemokines in the hypothalamus?

Increased body temperature

120

When do clinical problems start with the innate immune system?

When there is decreased phagocytosis

121

When may someone have decreased phagocytosis?

Decrease in spleen function
Decreased neutrophil number
Decreased neutrophil function

122

When may someone have decreased spleen function?

Asplenic/hyposplenic patients

123

When may someone have decreased neutrophil numbers?

Cancer chemotherapy
Certain drugs
Leukaemia and lymphoma

124

Give a drug that could lead to decreased neutrophil numbers

Phenytoin

125

When may someone have decreased neutrophil function?

Chronic granulomatous disease
Chediak-Higashi syndrome

126

Why does chronic granulomatous disease cause a decrease in neutrophil function?

No respiratory burst

127

Why does Chediak-Higashi syndrome lead to reduced neutrophil function?

No phagolysosome formation