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RM Principles > Immunology > Flashcards

Immunology Flashcards

1
Q

What is the general purpose of the immune system? (3)

A

Identify and eliminate microorganisms and pathogens
Recognise self and non-self signals
Recognise danger signals from acute inflammation

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2
Q

When is the function of the immune system at optimum effectiveness?

A

When it is balanced

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3
Q

What are the two consequences of an over-reactive immune system?

A

Autoimmune disease and allergic reaction

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4
Q

Define allergic reaction

A

Over-reaction of the immune system to a harmless substance

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5
Q

What are the two main consequences of an under-reactive immune system?

A

Susceptibility to cancer and infection

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6
Q

State the 5 factors that contribute to the emergence of new infectious diseases

A 
Travel
Loss of natural habitat
Population growth
Changes in human behaviour
Changes in interaction between pathogen and human
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7
Q

How does infection occur?

A

When the the body’s physical barriers to pathogens are breached

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8
Q

State the 6 properties of the skin that makes it an effective physical barrier to infection

A 
Tightly packed
Highly keratinised
Multi-layered cells
Low pH of 5.5
Low oxygen tension
Glands
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9
Q

State the 4 substances that the glands of the skin secrete

A

Hydrophobic oils
Ammonia
Antimicrobial peptides
Lysozyme

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10
Q

What are lysozymes

A

Enzymes that can break down bacterial cell walls

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11
Q

State generally where mucous is found in the body

A

All body cavities that are exposed to the external environment

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12
Q

State specifically three areas of the body where mucous is present

A

Respiratory tract
GI tract
Urogenital tract

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13
Q

State the 5 ways in which mucous stops pathogen invasion

A

Provides a physical barrier
Contains enzymes that kill pathogens
Contains secretory IgA which stops pathogens from attaching/entering cells
Contains lactorferrin that starves bacteria of iron
Cillia trap and clear pathogens

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14
Q

What kind of relationship do we have with commensal bacteria?

A

Symbiotic

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15
Q

State the 5 ways in which commensal bacteria provides a barrier to pathogens

A

Production of bactericidins
Reduction of pH in large bowel
Synthesis of Vitamin K and B12
Provide invading bacteria with competition for nutrients
Produce short chain fatty acids that have antimicrobial properties

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16
Q

What are commensal bacteria affected by? Give 3 examples

A

Changes in homeostasis, caused by things such age, malnutrition and intercurrent infections

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17
Q

How are commensal bacteria eliminated?

A

By broad-spectrum antibiotics

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18
Q

What are the three physical barriers (skin, mucous and commensal bacteria) known as and why?

A

Constitutive barrier as they are constantly there, regardless of if they are being used.

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19
Q

State the three overriding components of the immune system

A

Specialised cells, tissues and soluble factors.

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20
Q

What are the four requirements of the immune system?

A

Identification and response system of self and non-self antigens
Ability to modify its response to different pathogens
Actively promote tissue repair and healing after the pathogen has been eliminated
Immunological memory - remember pathogens

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21
Q

State the two components of the immune system

A

The hummoral response and the cell mediated response

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22
Q

What is the hummoral response mediated by?

A

Soluble macro-molecules (lipids and proteins) that are found in extracellular secretions

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23
Q

What is the cell mediated response mediated by?

A

Leukocytes

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24
Q

State the 4 components of the hummoral response

A

Cytokines
Complement system proteins
Acute phase proteins
Antibodies

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25
Q

State the three classes of cells involved in the cell mediated response

A

Phagocytes
Lymphocytes
Mast cells, eosinophils and basophils

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26
Q

What are the 3 cells involved in phagocytosis?

A

Neutrophils
Macrophages and Monocytes
Dendritic Cells

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27
Q

State the 3 lymphoctyes

A

T cells
B cells
Natural killer cells

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28
Q

What 4 components of the immune system are utilised in response to a virus?

A

Cytokines
Antibodies
Cytotoxic T cells
NK cells

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29
Q

What is the response to a parasitic worm? (4)

A

Mast cells
Eosinphils
Basophils
Antibodies

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30
Q

What is the response to intracellular bacteria and parasites? (3)

A

NK cells
CTL
Antibodies

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31
Q

What is CTL?

A

Cytotoxic T cell / Cytotoxic T Lymphocyte

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32
Q

What is the response to extracellular bacteria, parasites and fungi? (6)

A 
Neutrophils
Macrophages
Complement
Antibodies
CTL
NK cells
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33
Q

What are the two types of tissues that are involved in the immune system?

A

Primary lymphoid tissue and secondary lymphoid tissue

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34
Q

What happens at primary lymphoid tissue?

A

Leukocytes are developed

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35
Q

What are the two primary lymphoid tissues?

A

Bone marrow

Thymus

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36
Q

What are leukocytes synthesised from?

A

A single haemopatic stem cell

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37
Q

What is special about the haemopatic stem cell?

A

It has the ability to differentiate into all types of leukocytes

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38
Q

What happens after mitosis for a haemopatic stem cell?

A

One daughter cell differentiates and the other undergoes mitosis again

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39
Q

What does these two fates of a haemopatic stem cell mean?

A

That it is a constantly self-renewing process

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40
Q

What is the secondary lymphoid tissue?

A

Where the adaptive immune response is activated

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41
Q

State the 6 secondary lymphoid tissues

A 
Spleen
Lymph nodes
Adenoid
Tonsils
Peyers patch
Large intestine
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42
Q

What/where is the adenoid?

A

Lymphatic tissue at the back of the nose/throat

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43
Q

What is the consequence of an obstruction in lymphatic ducts?

A

Lympodema

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44
Q

What is the danger to tissue affected by lymphodema?

A

It is at high risk of infection

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45
Q

What are cytokines?

A

Small proteins or peptides

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46
Q

What three things are they produced in response to?

A

Inflammation
Infection
Tissue damage

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47
Q

What is the key role of cytokines in the immune system and why?

A

Coordination of immune response

Due to ability to modulate the behaviour of cells

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48
Q

How long-lived are cytokines?

A

Short-lived

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49
Q

Where do cytokines act in the body?

A

Both locally and systemically

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50
Q

What cytokine is produced in response to a viral infection?

A

Interferon

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51
Q

What are the two functions of interferon?

A

Antiviral protein production

Immunoactive cytokine production

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52
Q

What are antibodies composed of?

A

Protein

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53
Q

What are antibodies produced by, and why?

A

Antigen activated B cells, in response to the presence of an antigen

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54
Q

What are antigens?

A

Any substance that can stimulate an immune reaction

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55
Q

What three things do antibodies provide defense against?

A

Extracellular pathogens, viruses and toxins

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56
Q

How do antibodies prevent a viral infection?

A

They seek out and stick to the virus, meaning it cannot enter the cell

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57
Q

Where do T and B cells mature?

A

Bone marrow

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58
Q

Where do T and B cells go once they are mature?

A

The blood and lymphatic system

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59
Q

What is T and B cell’s primary role?

A

Search for non-self antigens

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60
Q

Which type of B and T cells are long-lived?

A

Memory T and B cells

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61
Q

What two things happen once a B or a T cell comes into contact with a non-self antigen?

A

They proliferate very quickly

Differentiate into their different cell types

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62
Q

What are B cells responsible for?

A

Production and secretion of antibodies

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63
Q

What type of pathogen is primarily attacked by T cells?

A

Intracellular pathogens

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64
Q

What are the type types of T cells, and what is their function?

A

Helper T cells - key regulators of the immune system

Cytotoxic T cells - kill virally infected cells

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65
Q

What is the gold standard for a vaccination?

A

A vaccination that stimulates both a B and T cell response

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66
Q

How does immunological memory occur?

A

Once the adaptive immune system has recognised and responded to a specific antigen

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67
Q

What two cells mediate immunological memory?

A

B and T cells

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68
Q

Describe natural killer cells

A

Large, granular lymphocytes

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69
Q

What are the three types of cells/other that NK cells are able to kill?

A

Tumour cells
Virally infected cells
Antigen bound pathogens and cells

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70
Q

What are the two ways in which NK cells are stimulated?

A

The presence of viral antibodies on a cell’s membrane

The absence of any antibodies on a cell membrane (ie. no self or viral antigens)

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71
Q

Where are mast cells present?

A

In tissues

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72
Q

What kind of tissue do mast cells protect and how?

A

Mucosal surfaces by attaching to large extracellular parasites

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73
Q

What is the function that mast cells play a key role in?

A

Allergic reaction

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74
Q

When the immune system is not being stimulated, where are eosinophils and basophils present, and how many are there?

A

Small numbers in the blood

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75
Q

What happens to the eosinophils and basophils when the body is infected by a parasite? (2)

A

They multiply rapidly and are recruited to the site of infection by inflammatory signals

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76
Q

What are mast cells, eosinophils and basophils responsible for? (3)

A

The recruitment and release of chemicals like histamine

Secretion of heparin and cytokines

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77
Q

What is the complement system?

A

A family of proteins

78
Q

Where are complement proteins produced?

A

In hepatocytes

79
Q

What state are complement proteins in when they are circulating in the body, and what are they known as?

A

Inactive

Precursor proteins

80
Q

When complement proteins become activated, what occurs?

A

A complement cascade.

81
Q

How does a complement cascade occur? (2)

A

First protein is stimulated to cleave into two parts, one of which is an enzyme.
Enzyme then cleaves second protein into two parts, one of which is an enzyme etc.

82
Q

What is at the bottom of a complement cascade and what 3 things can it do?

A

Components of the immune system that an attack pathogens, recruit and activate other cells

83
Q

What is the role of the complement system?

A

Promotion of inflammation and defense against certain bacterial species.

84
Q

State the 3 roles of the phagocytic cells

A

Ingestion and digestion of bacteria and fungi
Ingestion and clearance of debris from the body (immune complexes or apoptotic cells)
Sources of cytokines

85
Q

What are monocytes?

A

Precursors of macrophages

86
Q

What are the three life stages of a monocyte?

A

Circulate in the blood

Migrate to peripheral tissues where they differentiate into macrophages

87
Q

Describe macrophages (2)

A

Long-lived, tissue resident, phagocytic cells

88
Q

What the four different names for macrophages and where are these in the body?

A

Liver - Kupffer cells
Lung - Alveolar macrophages
Kidney - Mesangial cells
Nervous system - microglial cells

89
Q

What are the 6 functions of macrophages?

A

Limit inflammation/regulation of immune response
Tissue repair/wound healing
Antigen presentation
Clearance of debris from dead/dying cells
Ingest and kill extracellular pathogens
Regulate normal tissue homeostasis

90
Q

How can you identify neutrophils?

A

Bi or tri lobed nucleus

91
Q

What kind of life-span do neutrophils have and why?

A

Short, as they run out of nutrients

92
Q

How long is the life-span of a neutrophil?

A

6 hours

93
Q

Where are neutrophils recruited to? (3)

A

Inflamed, infected or damaged tissue

94
Q

What kind of cells are dendritic cells?

A

Phagocytic

95
Q

What are the three key roles of dendritic cells?

A

Engulf antigens
Engulf cellular debris
Antigen presentation

96
Q

What are the three life phases of dendritic cells?

A

Immature and in peripheral tissues
Activated when exposed to ‘phagocytose’ antigens
Migrate to secondary lymphoid tissue

97
Q

What is the key function of dendritic cells?

A

Bridge between innate and adaptive immune system

98
Q

What is the innate immune system responsible for?

A

The acute inflammatory response

99
Q

How quickly does the innate immune system act?

A

Very rapidly - within minutes to hours

100
Q

What kind of response is produced by the innate immune system (depending on what type of pathogen is present)?

A

The same response regardless of what the pathogen is

101
Q

State the 6 components of the innate immune system

A 
Acute inflammation
Macrophages
Mast cells
NK cells
Neutrophils
Complement system
102
Q

What effect does the innate immune system have on a pathogen (and what can it not do)?

A

Able to dampen the effect of the pathogen, but not eliminate the infection

103
Q

What kind of response is the adaptive immune system?

A

Unique response to each pathogen

104
Q

What is the adaptive immune system mediated by (2)?

A

T and B cells

105
Q

What is the adaptive immune system able to generate?

A

Immunological memory

106
Q

Describe how the dendritic cells bridge the innate and the adaptive immune system

A

Collects the antigens from the innate immune system response and presents them the the T and B cells of the adaptive immune system, therefore stimulating a response.

107
Q

What is required for both arms of the immune system to work together?

A

Biological communication

108
Q

Define immunodeficiency

A

Complete failure of the immune system

109
Q

How do chronic infections occur?

A

The pathogen is able to hide from the immune system, meaning it is not attacked fully.

110
Q

What happens to chronic infections?

A

They periodically reactivate and replicate.

111
Q

What are the two stages of a normal immune response?

A

The infection is cleared and the pathogen is remembered by the immune system

112
Q

State the two ways in which a pathogen can be recognised

A

Via direct contact and indirect contact

113
Q

Describe direct contact

A

The receptor on the immune cell will bind to and interact with ligands on the pathogen, therefore stimulating an immune response

114
Q

Give three examples of receptors and their ligand

A

TCR (receptor)- MHC
CD40 - CD40L
TLR4 - LPS

115
Q

Describe indirect contact

A

Injured cells and activated immune cells produce and secrete cytokines which alert and communicate with the immune system

116
Q

How is the immune system stimulated when there is a viral infection?

A

Virally infected cells produce interferon alpha and beta, which induces an antiviral state in the local environment and the cytokines act on other immune cells and neighbouring cells, instructing them to down regulate protein synthesis.

117
Q

Give three examples of the cytokines produced by viral infection

A

TNF-alpha
IFN-gamma
Inter-leukins

118
Q

Give the three stages of innate recognition and response

A

Recognition, activation and effector

119
Q

Specifically, what is recognised in the recognition stage of the innate response?

A

PAMPs - Pathogen associated molecular patterns

120
Q

What are PAMPs?

A

Signature molecules that are expressed by pathogens only, and never by humans

121
Q

How are PAMPs recognised?

A

Using PRRs

122
Q

What are PRRs?

A

Pattern Recognition Receptors

123
Q

Where are PRRs found?

A

Extracellularly and intracellularly

124
Q

What two things are involved in the activation and effector phases of the innate immune response?

A

Acute inflammation and pathogen killing

125
Q

Give two examples of extracellular PRRs and their associated PAMPs

A

Toll-Like Receptor 4 (TLR4) - Lipopolysaccharide (LPS)

Dectin 1 - Beta-glucans

126
Q

What are LPS found on?

A

Gram +ve bacteria

127
Q

What are Beta-glucans found on?

A

Fungi

128
Q

Give two examples of intracellular PRRs and their associated PAMPs

A

NOD2 - Muramyl dipeptide

TLR7 - ssRNA

129
Q

What pathogen has ssRNA?

A

Viruses

130
Q

What happens when the physical barriers of the immune system are breached and how?

A

Tissue resident innate immune system cells are activated through PAMPs and danger signals

131
Q

How does an autoimmune disease occur?

A

When macrophages fail to clear cellular debris

132
Q

State the 5 stages of phagocytosis/clearance of cellular debris

A
  1. Apoptotic cell sends out ‘find-me’ signals that activates and attracts macrophages
  2. Macrophages recognise ‘eat-me’ signals on the apoptotic cell surface
  3. Macrophages rearrange cytoskeleton and internalise the apoptotic cell
  4. Lysosomes fuse with the vesicle with the apoptotic cell, creating a phagolysosome
  5. Macrophage secretes anti-inflammatory mediators to prevent tissue damage
133
Q

What happens to the pathogens that the macrophage is unable to kill?

A

They stay in the phagolysosomes

134
Q

State the 3 pathogens that are able to evade killing by the macrophages

A

Salmonella
Staph, Aureus
Mycobacteria

135
Q

What happens when a pathogen is able to stay alive in the phagolysosome?

A

The macrophage becomes superativated

136
Q

What stimulates the superactivation of the macrophage?

A

Pro-inflammatory cytokines

137
Q

What two things does the superactivation of the macrophage do?

A

Stimulates the production of Reactive Oxygen Species and Reactive Nitrogen Species (ROS and RNS)
Increased presentation capability of macrophages

138
Q

What are the three systemic reactions to cytokines?

A

Hypothalamus - stimulated to produce prostaglandins = fever
Liver - Acute phase response
Long bones - increase neutrophil production

139
Q

What is the process of neutrophil production called?

A

Leukocytosis

140
Q

What are the three processes of pathogen killing?

A

Anti-microbial peptides
ROS
Phagocytosis

141
Q

What two things occur when the PRRs on Mast Cells are stimulated?

A

The mast cell degranulates

Production of new pro-inflammatory mediators

142
Q

What is the Acute Phase Response?

A

A systemic change in plasma concentrations of specific proteins

143
Q

What is the Acute Phase Response driven by?

A

Cytokines produced by localised inflammatory responses

144
Q

What organ stimulates the Acute Phase Response?

A

Liver

145
Q

What are the proteins involved in the acute phase response called?

A

Acute Phase Proteins

146
Q

What are the 5 biological roles of acute phase proteins?

A 
Preventing spread of infection
Diagnostic marker
Wound healing
Coagulation
Preventing systemic inflammation
147
Q

What acute phase proteins are involved with preventing the spread of infection and can be used as a diagnostic marker?

A

CRP
SAP (serum amyloid protein)
Complement protein

148
Q

What acute phase protein is involved in wound healing and coagulation?

A

Fibrinogen

149
Q

What 4 acute phase proteins are involved in preventing systemic infection?

A

CRP
Haptoglobin
Manganese superdioxide dismutase
Proteinase inhibitors

150
Q

What does CRP stand for?

A

C-reactive protein

151
Q

What is the structure of CRP?

A

Pentraxin - 5 identical subunits

152
Q

Clinically, what is CRP used for and why?

A

Marker of infection as it has a very short half life - so it is a very dynamic marker

153
Q

What does a larger amount of CRP indicate?

A

The severity and type of infection

154
Q

What are the two other roles of CRP?

A

Responsible for the initiation of the complement system

Enhances phagocytosis

155
Q

Where do pro-inflammatory mediators have an affect?

A

Local affect on the tissue near the production site

156
Q

What are the 4 key elements of acute inflammation?

A

Increase in vascular permeability
Vasodilation and increase in blood flow
Endothelial cell activation
Transendothelial migration and chemotaxis of neutrophils

157
Q

What are the pro-inflammatory mediators involved in the increase of vascular permeability? (7 - 3 from one cell, 4 from the other)

A

Macrophages - Nitric oxide, TNF alpha and IL-1

Mast cells - Histamine, TNF alpha, Prostaglandins and leukotrienes

158
Q

What two pro-inflammatory mediators are involved in vasodilation and increased blood flow? (2)

A

TNF alpha (macrophages) and Histamine (mast cells)

159
Q

What is endothelial activation?

A

The expression of Selectins (receptors) and ICAM1/VCAM1 (ligands)

160
Q

What is the consequence of endothelial activation?

A

Leukocytes stick to endothelial cells that are around the inflammation site

161
Q

What chemical is involved in chemotaxis and what do they do?

A

Chemokines - family of cytokines that guide migration in chemotaxis

162
Q

What is rolling?

A

When neutrophils bind weakly to selectin that is expressed on endothelial cells

163
Q

What happens to rolling when ICAM/VCAM are expressed?

A

The leukocytes binds tightly to endothelial cells

164
Q

What processes does the neutrophil go through to get through the endothelial cells?

A

Diapodesis

165
Q

What is diapedesis?

A

Where the neutrophil changes shape and migrates through the blood vessel walls

166
Q

What are the two key structural features of neutrophils?

A

Intracellular granules and multi-lobed nucleus

167
Q

How do neutrophils get to the site of inflammation?

A

Recruited by pro-inflammatory mediators

168
Q

What are the 3 ways in which neutrophils can kill pathogens?

A

NETs
Degranulation
Phagocytosis

169
Q

How is phagocytosis initiated?

A

By pathogens secreting chemokine-like signals

170
Q

What are the two methods of phagocytosis?

A

Anti-microbial proteins

NADPH oxidase dependant mechanisms

171
Q

Describe phagocytosis via anti-microbial proteins

A

Proteins contained within granules fuse with the encapsulated pathogen

172
Q

Describe the steps involved in NADPH oxidase dependant mechanism

A

Neutrophil is acitvated
Assembly of NADPH oxidase complex
Production and release of ROS into the phagolysosome

173
Q

What is the NADPH oxidase dependant mechanism known as?

A

The respiratory burst

174
Q

What are NETs?

A

Neutrophil Extracellular Traps

175
Q

How are NETs used to fight infection?

A

Released by activated neutrophils into the extracellular environment

176
Q

What 3 effects do NETs have on pathogens?

A

Immobilises pathogen
Prevents the spread of the pathogen
Facilitates its phagocytosis

177
Q

What is degranulation?

A

The secretion of the anti-microbial proteins into the extracellular environment

178
Q

What is the positive and what is the negative of degranulation?

A

Positive - direct killing of pathogen

Negative - can cause tissue damage and systemic inflammation

179
Q

How can complement proteins be activated?

A

Directly or indirectly by a pathogen

180
Q

What are the three ways in which a complement protein can be broken down?

A

Mannose-binding lectin pathway
Alternative pathway
Classical pathway

181
Q

Where is mannose found?

A

On bacterial cell membranes

182
Q

Where is MBL produced and why is it produced?

A

Liver - as part of the acute phase response

183
Q

What happens when mannose is recognised?

A

The cleaving of complement proteins is initiated

184
Q

What are the four consequences of the complement cascade?

A

Pathogen killing
Leukocyte recruitment
Removal of immune complexes
Pathogen opsonisation

185
Q

What is opsonisation?

A

The coating of pathogens in hummoral factors (opsonins) to facilitate phagocytosis

186
Q

Which complement proteins are involved in leukocyte recruitment?

A

C3a and C5a

187
Q

What are C3a and C5a known as?

A

Anaphylatoxins

188
Q

What are the two target sites for C3a and C5a?

A

Blood vessels and mast cells

189
Q

How does pathogen killing occur with complement proteins?

A

C3b cleaves C5, which attached to the pathogen surface, initiating membrane attack complexes

190
Q

How is the complement cascade initiated?

A

By C3 being cleaved into C3a and C3b

RM Principles (5 decks)

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