Intro to immunology Flashcards

1
Q

Define innate immunity

A

Non-specific, distinctive and does not depend on lymphocytes

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2
Q

Define adaptive immunity

A

Specific acquired immunity, requires lymphocytes and antibodies

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3
Q

Define humeral immunity

A

Mediated by macromolecules found in ECF such as antibodies and complement proteins

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4
Q

Size of Neutrophils

A

10-14 micrometer

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5
Q

How many Neutrophils per mm^3 blood

A

3-11,000

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6
Q

Life span of neutrophils

A

6hours-12 days

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7
Q

What adhesion molecule is produced by neutrophils

A

CD66b

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8
Q

What immunity do neutrophils have a great role in

A

Innate

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9
Q

What are the two main intracellular granules in neutrophils

A

Primary lysosomes - myleloperoxidase, muramidase, acid hydrolyses and defensives

Secondary lysosomes (lysozyme and lactoferrin)

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10
Q

Role of primary lysosomes

A

Combine with phagosomes containing microbes to digest them
Complement receptors
Secrete superoxides

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11
Q

Why are myeloperoxidases needed

A

Allows neutrophils to carry out antimicrobial activity

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12
Q

Why are superoxides needed

A

Kill microbes

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13
Q

Size of monocytes

A

14-24 micrometers

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14
Q

How frequent are monocytes

A

100-700 per mm^3 blood

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15
Q

Lifespan of monocytes

A

Months

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16
Q

What receptors do monocytes express

A

CD14

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17
Q

Role of monocytes

A

Innate and adaptive immunity
Phagocytosis
Ag Presentation

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18
Q

What happens to monocytes after entering the tissues

A

Differentiate into macrophages

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19
Q

What compound are contained in monocyte lysosomes

A

Peroxidase

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20
Q

What receptors do monocytes have

A
  1. FC
  2. Complement receptors
  3. PRR
  4. Toll-like
  5. Mannose receptors
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21
Q

What do FC receptors bind to

A

Antibodies that are attached to infected cells or invading pathogens

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22
Q

Where do macrophages reside

A

Tissues

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23
Q

Lifespan of macrophages

A

Months/years

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24
Q

What type of macrophage are found in the liver

A

Kupffer cells

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25
Q

What type of macrophage are found in the brain

A

Microglia

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26
Q

Role of macrophages

A

Phagocytosis and Ag presentation

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27
Q

What cells are the first line of non-self recognition

A

Macrophages

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28
Q

Main role of macrophages

A

Remove microbes and tumour cells

Present Ag to T-cells

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29
Q

What enzyme is found in macrophage lysosomes

A

Peroxidase

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30
Q

Size of an eosinophil

A

10-14 micrometer

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31
Q

Frequency of eosinophil

A

100-400 per mm^3 blood

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32
Q

Lifespan of eosinophil

A

8-12 days

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33
Q

What receptors do eosinophils express

A

CD125

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34
Q

Role of eosinophils

A

Associated with parasitic infections and allergic reactions

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35
Q

What is contained in eosinophil granules

A

Major Basic Protein - potent toxin for helminth worms

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36
Q

Role of MBP

A

Activates neutrophils
Induces histamine release from mast cells
Provokes bronchospasm

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37
Q

Size of basophil

A

10-12 micrometer

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38
Q

Frequency of basophil

A

20-50 per mm^3 blood

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39
Q

Lifespan of basophil

A

2 days

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40
Q

What cell are basophils similar to

A

Mast cells

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41
Q

What receptors do Basophils express?

A

FcεR1 (IgE receptors)

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42
Q

What happens when IgE binding occurs

A

Degranulation - releases histamine

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43
Q

Role of basophils

A

Response to parasitic infections and allergic reactions

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44
Q

Size of mast cell

A

10-14 micrometers

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45
Q

Where are mast cells active

A

Only in tissues - circulates inactive form in the blood

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46
Q

What receptors do mast cells have

A

FcεR1

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47
Q

What happens when IgE its bound to

A

De-granulation releasing histamine

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48
Q

Size of T cells

A

5-12 micrometer

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49
Q

Frequency of T cells

A

300-1500 per mm^3 blood

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50
Q

Lifespan of T cells

A

hours to years

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51
Q

Where do T cells mature

A

Thymus

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52
Q

What receptor do T lymphocytes express

A

CD3

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53
Q

Role of T helper cells 1

A

Immune response to intracellular pathogens

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54
Q

Receptor on T helper cells 1

A

CD4

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55
Q

Role of T helper cells 2

A

Produce antibodies - extracellular pathogens

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56
Q

Receptors on T helper cells 2

A

CD4

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57
Q

Role of cytotoxic T cells

A

Kill cells directly

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58
Q

Receptor on cytotoxic T cells

A

CD8

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59
Q

Role of T regulatory cells

A

Regulate immune responses ‘dampen’

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60
Q

Receptors on T regulatory cells

A

FoxP3

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61
Q

Where are T cells found (3)

A
  1. Blood
  2. Lymph nodes
  3. Spleen
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62
Q

Size of B cells

A

5-12 micrometer

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63
Q

Frequency of B cells

A

300-1500 per mm^3 blood

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64
Q

Lifespan of B cells

A

Hours to years

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65
Q

Where do B lymphocytes mature

A

Bone Marrow

66
Q

What receptors do B cells express

A

CD19 and CD20

67
Q

Role of B cells

A

Recognise Ag displayed by APC
Express membrane bound antibody on cell surface
Differentiate into plasma cells that make antibodies

68
Q

Where are B cells found

A

Blood
Lymph Nodes
Spleen

69
Q

What receptor do NK cells express

A

CD56

70
Q

Where are NK cells found

A

Spleen/tissues

71
Q

Role of NK cells

A

Kill virus infected cells
Tumour cells

by triggering apoptosis

72
Q

How many compliment factors are present in the immune system

A

20

73
Q

Classification of complement factors

A

Classical
Alternative
Lectin

74
Q

Two properties of antibodies

A
  1. Bound to b cells

2. Soluble

75
Q

Name the 5 distinct classes of antibodies

A
  1. IgG
  2. IgA
  3. IgM
  4. IgD
  5. IgE
76
Q

Define antibody

A

Protein produced in response to an antigen

77
Q

Define antigen

A

A molecule that reacts with preformed antibody and specific receptors on T and B cells

78
Q

Define Epitope

A

Part of an antigen that binds to the antibody/receptor binding site

79
Q

Define affinity

A

Measure of binding strength between an epitope and an antibody binding site

80
Q

Most common antibody in the body

A

IgG

81
Q

How many chains is IgG made of

A

4 peptide chains: Two heavy and two light joined by disulphide bonds

82
Q

Role of Fab fragment on antibody

A

Binds to antigens (the light and heavy chain ends of the antibody - or tips of the Y shape)

83
Q

Proportion of antibodies in the blood made up by IgM

A

10%

84
Q

Shape of IgM

A

Pentagon

85
Q

How are the chains of IgM attached together

A

J chains

86
Q

Where is IgM mainly found

A

Blood

87
Q

Can IgM move into tissues and why

A

No, too big to pass through endothelium

88
Q

Role of IgM

A

Initial contact with Ag

89
Q

What is the purpose of the monomeric form (mIgM)

A

It acts as an antigen-specific receptor on B cells

90
Q

Proportion of antibodies in the blood made up by IgA

A

15%

91
Q

Is IgA a dimer

A

No, it’s mostly a monomer in humans (80% of them are)

92
Q

Where is IgA commonly found

A

Saliva, milk and genitourinary secretions (known as sIgA)

93
Q

How is sIgA held together

A

J chain and secretory component

94
Q

Proportion of antibodies in the blood made up by IgD

A

1%

95
Q

Where is IgD found

A

Mature B cells (transmembrane monomeric form)

96
Q

Proportion of antibodies in the blood made up by IgE

A

0.05%

97
Q

Role of the cytokine IFN (Interferons)

A

Induce a state of antiviral resistance in uninfected cells

Limit spread of viral infections

98
Q

What cells produce IFN alpha and beta

A

Viral infected cells

99
Q

What secretes IFN gamma

A

Released by activated TH1 cells

100
Q

What is the pro-inflammatory interleukin

A

IL1

101
Q

What is the anti-inflammatory interleukin

A

IL-10

102
Q

Role of IL

A

Causes cells to divide, differentiate and secrete factors

103
Q

Role of Colony Stimulating Factors

A

Involved in directing division and differentiation on bone marrow stem cells

104
Q

What are CSF precursors of

A

Leukocytes

105
Q

Role of TNF

A

Mediate infiammatorio and cytotoxic reactions

106
Q

Role of chemokine

A

Direct movements of leukocytes from blood stream into tissues or lymph organs by binding to specific receptors on cells

107
Q

What do CXCL act on

A

Neutrophils, T and B cells

108
Q

What do CCL act on

A

Monocytes, lymphocytes, eosinophils and basophils

109
Q

What do CX3CL act on

A

T and NK cells

110
Q

What do XCL act on

A

T cells

111
Q

What is innate immunity composed of

A

Barrier to pathogens

112
Q

What is the main component of adaptive immunity

A

Memory cells

113
Q

What barriers does the innate immunity use to defend against pathogens

A

Dermis and Epidermis

Skin secretions (pH 3-5)

114
Q

Use of tears in pathogenic defences

A
  1. Lysosomes present
115
Q

What is the purpose of mucous membranes

A
  1. Saliva and tears and mucous secretions can trap bacteria

2. Cilia beats microbes away

116
Q

What physiological barriers are there for pathogenic defence

A
  1. Pyrexia Prevents micro-organism growth
117
Q

Role of gastric acidity in innate immunity

A

Destroys pathogens

118
Q

How does gastric acidity effect children vs adults

A

Less acidic in children so susceptible to infection

119
Q

What are the three physiological factors of the innate immunity

A

pH
Gastric Acidity
Oxygen Tension

120
Q

What follows breach of pathogens following failure of innate immunity

A

Inflammation

121
Q

Define acute inflammation

A

Complete elimination of a pathogen followed by resolution of damage, disappearance of leukocytes and full regeneration of tissue

122
Q

What two ways can microbes detect microbes

A
  1. PRR on host cells identified
  2. Identify PAMPs on microbes (molecules produced by pathogens or abnormal activity caused by them)
  3. Toll-like receptors on leukocytes allows recognition
123
Q

Three roles of the complement system

A
  1. Lyse microbes directly (membrane attacking)
  2. Increase chemotaxis (C3a and C5a)
  3. Opsonisation (C3b)
124
Q

How does chemoattraction take place in extravasation

A

Cytokines cause endothelial cells near site of infection to express cellular adhesion molecules (selection)

125
Q

Describe the adhesion process of extravasation

A
  1. Ligans on leukocytes bind to selection with small affinity, slow down and roll along inner wall
  2. Chemokines released by macrophages activate rolling leukocytes and cause surface intern molecules to go from low to high affinity
126
Q

What two pathways exist in macrophage and neutrophil killing

A

Oxygen dependant

Oxygen indépendant

127
Q

Describe the Oxygen dependant pathway

A

Superoxides converted to hydrogen peroxides and hydroxide ions
NO also produced which causes vasodilation for extravasation

128
Q

Describe the oxygen independent mechanism of killing

A

Defensives insert into pathogenic membranes and lysozyme change pH

129
Q

Where is C reactive protein produced

A

Liver

130
Q

Role of C reactive proteins

A

Binds to bacterial cell walls

Promotes opsonisation

131
Q

What do C reactive proteins bind to

A

C1q receptors to activate complement system

132
Q

Role of Mannose binding Lectin

A

Binds to lectin and promotes opsonisation

Activates complement system

133
Q

Role of surfactant protein-A

A

Binds haemagglutinin in influenza - reduces ability of virus to infect cells

134
Q

What cell protects against intracellular microbes

A

T cells

135
Q

What cell protects against extracellular microbes

A

B cells

136
Q

Do T cells respond to soluble antigens

A

No

137
Q

What is T cell selection

A

T cells recognise self antigens and are killed in the thymus as they mature

138
Q

What structure are T cell receptors similar to

A

Fab structure on Ig antibodies

139
Q

What is the role of the Major Histocompatibility Complex

A

Display peptides from self or non-self proteins on the cell surface - invasion alert

140
Q

Where are MHC I glycoproteins found

A

ALL nucleated cells

141
Q

Where are MHC II glycoproteins found

A

ONLY on APC

142
Q

Where are MHC III found

A

Complementary system

143
Q

What are MHC I and II coded by

A

HLA

144
Q

How do the MHC interact with the T cells

A

MHC molecule presents peptide which is recognised by T cell when they bind

145
Q

How many AA are in MHC I

A

8-10

146
Q

How many AA are in MHC II

A

13-24

147
Q

What cells do MHC I interact with

A

CD8 T cells

148
Q

What happens when MHC I of host cell binds to CD8

A

Infected cell with intracellular pathogen is destroyed

149
Q

What do MHC II bind to

A

CD4

150
Q

What happens when MHC II of host cell binds to CD4

A

Help B cells make Ab to extracellular pathogen and help directly kill

151
Q

Describe the process of Ag Recognition and Activation of T cells

A
  1. CD28 on T cell binds to CD80/86 on APC

2. IL-2 secreted and binds to IL-2 receptor on T cells (autocrine) activating T cell.

152
Q

How can CD4 further differentiate

A

Into TH1 due to IL-12hi

Into TH2 due to IL-12lo

153
Q

Role of IFN gamma

A

Kill intracellular pathogens

154
Q

From what cells are IFN-gamma produced

A

TH1

155
Q

Describe the activation of CD8

A
  1. MHC I binds to TCR on inactive CD8
  2. CD8 matures and releases chemokine
  3. Releases perforin and granulising
156
Q

Role of perforin

A

Apoptosis

157
Q

Role of granulysin

A

Killing pathogens

158
Q

Describe activation of CD4

A
  1. APC presents Ag with MHC to naive CD4
  2. High levels of IL-12 cause naive CD4-> mature CD4
  3. Clonal expansion
  4. CD4 recognises Ag on infected cells via re ephors
  5. CD4 secretes INF gamma which induces apoptosis
159
Q

How many immature B cells are we born with

A

10^9

160
Q

Describe the process of Antigen presenting of B cells to T cells

A
  1. IgM binds Ag
  2. Phagocytosis
  3. Peptide displayed with MHC II
  4. CD4 binds to MHC II
  5. APC eats Ag and presents to CD4 and T cells via MHC II
  6. CD4 turn into T-helper 2 cells
  7. TH2 secretes IL4, 5, 10 and 13
  8. Clonal Expansion of B cells -> Plasma cells and Memory B cells