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Foundations in Medicine 1 > Immunology > Flashcards

Immunology Flashcards

1
Q

What do living organisms consist of

A

Plants animals micro-organisms (bacteria, fungi, algae and protozoa)

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2
Q

Name two pathogenic eukaryotes

A

fungi and protozoa

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3
Q

Name a pathogenic prokaryote

A

bacteria

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4
Q

What are viruses?

A

non-living/ small obligate parasites

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5
Q

Name three differences between prokaryotes and eukaryotes

A

eukaryotes are much more compartmental so have specific organelles that perform specific functions they also have linear chromosomes and histone proteins compared to the singular circular chromosome in prokaryotes etc etc etc

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6
Q

Name the 6 properties of the prokaryotic cell

A

plasma membrane, cell wall, nucleoid, ribosomes, cytoplasm and capsule/flagellar or pili

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7
Q

Name the different properties of a eukaryotic cell

A

cell membrane, nucleus, centriole, nucleus, ribosomes, ER, cytosol, mitochondria, golgi, cytoskeleton, secretory vesicle/lysosomes etc etc

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8
Q

Name three different barriers to infection in the body

A

skin, mucus and commensal bacteria

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9
Q

How does skin provide a barrier to infection

A

Physical barrier of tightly packed keratinised (makes it waterproof) multiple-layered epithelium, has low pH, secrete lysozymes, antimicrobial peptides and hydrophobic oils to prevent the survival of pathogens

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10
Q

How does Mucus provide a barrier to infection

A

cilia (traps and expels via coughing etc) secretory IgA, physical barrier (thick consistency), lactoferrin starves the bacteria of iron

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11
Q

Name 3 types of mucus membranes

A

respiratory, gastrointestinal and urogenital

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12
Q

What are commensal bacteria

A

Bacteria that are present in the microbiota that do not cause harm and are often involved in miantaining health of the individual

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13
Q

What is innate immunity

A

the first line of defence which is non-specific

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14
Q

What is adaptive immunity

A

specific more tailored in response to foreign non-self particles

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15
Q

Give examples of cells involved in the innate immune response

A

neutrophils, macrophages, mast cells and NK cells

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16
Q

What cells are involved in the adaptive (acquired) immune response

A

T and B lymphocytes and DCs (bridge between innate and adaptive)

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17
Q

What are the functions of a macrophage

A

they’re anti-inflammatory; phagocytosis, degradation of pathogens in the lysozyme vacuole, antigen presentation and wound healing/tissue response

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18
Q

What is the role of mast cell

A

involved in allergy + parasitic infections , secretes histamine, pro inflammatory

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19
Q

NK cell roles

A

Destruction of virally infected cells as well as cancer cells

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20
Q

What are PAMPs

A

pathogen-associated molecular patterns, molecules expressed on non human cells

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21
Q

Give examples of of PAMPs

A

LPS, viral dsRNA, beta glycans from fungi and bacterial cell walls

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22
Q

What are PRRs

A

Pattern recognition receptors, are present on immune cells and recognise pathogens and pathogenic material

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23
Q

what is pinocytosis

A

ingestion of fluid from surroundings

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24
Q

what is receptor mediation endocytosis

A

when the membrane-bound receptors are internalised into the cell - important for adaptive immunity later on

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25
Q

Describe the steps of Phagocytosis

A

PRR engages with PAMP and signals relased into cell, rearranges the cytoskeleton to “cup” around the pathogen and internalise it into a phagosome which fuses with a cytosolic lysozyme (acidic pH) allowing it to breakdown the pathogen, debris is released into extracellular fluid and the cytokine TNalpha is released

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26
Q

What is phagocytosis

A

specific endocytosis which internalises solid matter such as apoptotic cells as well as microbial pathogens

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27
Q

Give examples of opsonins

A

C3b, IgG, IgM and CRP

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28
Q

What is opsonisation

A

the coating of pathogens by soluble factors (opsonins) to enhance phagocytosis

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29
Q

Upon recognition of a pathogen what do mast cells do?

A

Release pre-existing histamine in the cell as well as gene expression for the production of prostaglandins and leukotrienes

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30
Q

What is acute inflammation

A

response to cellular injury or infection

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31
Q

Under homeostasis neutrophils are found circulating in the blood

A

true

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32
Q

How do neutrophils leave the circulation and migrate to the tissue of interest?

A

neutrophils circulating will express LFA-1 and weakly bind to selectins and then stable adhesion to ICAM-1 on endothelial cells and cells move through the tissue via chemotaxis and activated by TNFa and PAMPs

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33
Q

Endothelial cells express adhesion molecules during inflammation to slow down WBCs

A

true

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34
Q

Name three ways neutrophils can kill pathogens

A

NETs, phagocytosis and degranulation

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35
Q

what do interferons do during an anti-viral response

A

cause neighbouring cells to reduce protein production/RNA synthesis, induce programmed cell death and activate NK cellsl,

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36
Q

What is oxygen dependent killing in neutrophils

A

assembly of NADPH oxidase complex recruits the ROS and released into the granules to degrade pathogen

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37
Q

What is oxygen-independent killing of neutrophils

A

granules fuse with the phagosome and reduce pH and induce bacterial killing

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38
Q

What is the function of lactoferrin

A

competes with bacteria to bind to iron

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39
Q

what are lysosomes

A

granules that degrade the cell wall of gram -ve bacteria

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40
Q

What cytokines are good for viral responses

A

IFNa and b

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41
Q

What are NETs

A

a form of neutrophil suicide that helps immobilise pathogens

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42
Q

What process by neutrophils immobilises the pathogen preventing it from spreading as well as making it available for oppsonisation

A

NETs

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43
Q

What is your pus made out of

A

neutrophils

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44
Q

NK cells recognise self-peptides using MHC II, true or false?

A

False, it is via MHC I

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45
Q

Once activated NK cells produce what

A

perforin which creates pores in the recipient cell causing apoptosis

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46
Q

How do NK cells recognise self-peptides

A

through the inhibitory receptor which upon activated prevents any of the killing mechanisms in the cell

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47
Q

Where are acute-phase proteins made?

A

liver

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48
Q

What are examples of acute-phase proteins?

A

CRP and C3 and MBL (complement proteins)

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49
Q

What is the function of CRP

A

functions as an opsonin to enhance phagocytosis by other immune cells

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50
Q

What is the diagnostic importance of CRPs

A

their levels in the blood can indicate the severity of inflammation/illness

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51
Q

What is the MBL pathway does the activation of C3b and C3a occur in the MBL pathway

A

A MBL binds to the mannose found on bacteria recruiting C3 covertase to covert the inactive C3 to the active forms C3a and C3b

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52
Q

What complement protein is the prerequisite for the membrane attack complex

A

C5b

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53
Q

What complement protein induces the cleavage of C5 to C5a and C5b

A

C3b

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54
Q

What is the function of C3a and C5a

A

amplification of acute inflammation - changes in local vasculature (vasodilation and expression of adhesion molecules), activation of mast cells

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55
Q

What complement protein is a powerful opsonin?

A

C3b

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56
Q

What cell is known as the bridge between the innate and adaptive immune response?

A

dendritic cell

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57
Q

What is the function of B cells?

A

antibody production and responsible for the humoral immune response key in defending against extracellular pathogens

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58
Q

What is the function of T cells?

A

defence against intracellular pathogens

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59
Q

What are CD4+ T cells?

A

helper T cells that help coordinate/regulate the immune response

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60
Q

What are CD8+ T cells?

A

cytotoxic T cells that induce cell killing of virally infected cells

61
Q

What is it meant by specific recognition of B and T cells

A

they only express one antigenic receptor that binds to one specific antigenic epitope

62
Q

What is the molecular structure of an antibody

A

A heavy chain and a light chain are held together by disulphide bonds, each chain containing a variable region and a constant region

63
Q

What region determines the specificity in antibodies?

A

variable region

64
Q

What consists of the antigen binding site on a B cell?

A

variable regions of a the heavy and light chains

65
Q

What receptor is made up of a heterodimer of alpha and beta chains

A

TCR

66
Q

CD8+ T cells recognise MHC II molecules, true or false?

A

false, they recognsie MHC I

67
Q

What MHC Class do CD4+ T cells recognise?

A

MHC II

68
Q

What cells express MHC II

A

professional antigen-presenting cells such as DCs, macrophages and B cells

69
Q

What class of MHC is expressed on all nucleated cells?

A

MHC I

70
Q

Where are B and T cells originated

A

bone marrow

71
Q

T cells complete their maturation in the thymus, true or false?

A

true, they develop in the bone marrow and then travel to the thymus to complete development

72
Q

What are primary lymphoid tissues

A

bone marrow and thymus

73
Q

What are the spleen, lymph nodes and peyer’s patch known as?

A

secondary lymphoid tissues

74
Q

What are T and B cells doing if they don’t meet their specific antigen

A

circulating through blood and lymph between tissues and lymphoid organs

75
Q

How do B cells encounter antigens?

A

stromal cells of the B cell zones bind to opsonins and hold them for weeks for circulating B cells to hopefully arrive and encounter their specific antigen

76
Q

How do T cells encounter antigen?

A

dendritic cells internalise pathogens inside and then present the antigens on their MHC I or II, TNFa increases costimulatory expression on these cells and they travel to the lymph node presenting these antigens to their antigen-specific T cells

77
Q

What Ig is secreted by short-lived plasma cells

A

low affinity IgM

78
Q

What is affinity maturation?

A

the rearrangement of the variable region of the antibody to become more specific

79
Q

What is class switching

A

By rearrangement or changing of the constant chain of the antibody

80
Q

Which is the most versatile antibody in terms of its functions?

A

IgG

81
Q

What are the two weaker costimulatory methods for B cells?

A

non protein antigens - BCR and antigen and PRR and PAMP
repeating antigenic epitopes of BCR and antigen (polysaccharide/fatty acid etc)

82
Q

What is the most optimum costimulatory method for B cells?

A

B cells use Ab to bind to opsonin and the MHC II binds to the TFhelper cell as the costimulatory interaction which causes proliferation and class switching/affinity maturation

83
Q

germinal centre tends to be the derived area where lymphomas and leukaemia arise relating to the mutations that occur in this area, true or false

A

true

84
Q

What antibody is present as a pentameric structure and involved in agglutination and complement activation

A

IgM

85
Q

What is agglutination?

A

cross-linking of multiple antigens by the antibodies creating larger lumps

86
Q

What is the importance of agglutination?

A

Prevents the spread of viruses and increases the efficacy of phagocytosis

87
Q

Which antibody forms the C1 complex

A

IgM

88
Q

What are the six functions of IgG

A

agglutination
complement activation
foetal immune protection
neutralisation
opsonisation
NK cell activation

89
Q

What antibody can be transported across the placenta?

A

IgG

90
Q

Which antibodies are involved in Neutralisation?

A

secretory IgA and IgG

91
Q

What is neutralisation?

A

binding to the pathogen thereby;
blocking attachment to the cell
blocking endocytosis
blocking uncoating and releasing RNA into the cell

92
Q

What is opsonisation?

A

IgG binds to the pathogen and phagocytes express fc receptors that binds to the constant region of the IgG; therefore enhances phagocytosis

93
Q

Which is the second most abundant antibody in the blood?

A

IgA

94
Q

Which antibody is present as a dimeric form in secretions such as breast milk and mucus?

A

IgA

95
Q

Which antibody is involved in allergic response?

A

IgE

96
Q

What cells express fc receptors for IgE?

A

mast cells and basophils

97
Q

Which is the effector region of the antibody

A

heavy chain constant region

98
Q

which is the recognition region/antigen binding site of the antibody?

A

variable region on both the heavy and light chains

99
Q

Name a type of specialised DC

A

Langerhans cells

100
Q

What indicates the maturation of dendritic cells?

A

expression of costimulatory molecules

101
Q

DCs only present on MHC II, true or false?

A

False, They present on both as they are nucleated cells but are also antigen-presenting cells

102
Q

what cytokine do activated CD4+ cells produce

A

IL-2

103
Q

What is the function of IL-2

A

promote proliferation and clonal expansion of T cells

104
Q

What is the function of Th1 cells?

A

release of proinflammatory cytokines to enhance macrophage-mediated killing

105
Q

What is the fucntion of Tfh cells?

A

stimulate clonal expansion of B cells upon recognition of its specific antigen

  • these B cells differentiate into long-lived plasma cells (high affinity antibodies) and memory B cells
106
Q

What does the IFNg secretion by a Th1 cell to macrophage cause?

A

induce gene expression of the NADPH oxidase complex to enhance oxygen-dependent killing

107
Q

What is the function of CD8+ T cells?

A

induce apoptosis in target cells expressing foreign molecules on MHC I

108
Q

How do CD8+ T cells induce the killing of an infected cell?

A

bind to the peptide presented on MHC class I and release perforin and granzymes to induce apoptosis

109
Q

what is the role of perforin

A

polymerises to form a pore in the membrane of a cell

110
Q

What are granzymes

A

serine proteases that activate apoptosis once in the cytoplasm of the target cell

111
Q

Define immunisation

A

the process by which an individual develops immunity to a disease

112
Q

Define vaccination

A

the deliberate administration of antigenic material to produce immunity to a disease

113
Q

What cell is important for resolution of an immune response?

A

macrophages

114
Q

How are macrophages important in a an active process of immune resolution?

A

anti-inflammatory cytokines such as IL-10, tissue repair by releasing growth factors that help with wound repair by creating more cells

115
Q

What is herd immunity

A

the goal to vaccinate everyone in the population that can be and is healthy enough to in order to protect those who are unable to receive the vaccine

116
Q

Name the four classifications by Gel and Coombs of hypersensitivity

A

Type I: Immediate hypersensitivity (allergy)
Type II: Direct cell effects (cellular effects)
Type III: Immune complex-mediated
Type IV: Delayed type hypersensitivity

117
Q

What’s the difference between allergy and sensitivity?

A

allergies have circulating IgE for the specific antigen, sensitivities do not

118
Q

What type of T cell is involved in allergy?

A

Th2 cells

119
Q

what cytokines are secreted by Th2 cells?

A

IL-4, IL-5 and IL-13

120
Q

What happens upon reexposure to the allergen?

A

mast cells or basophils containing IgE bound to their fc receptors causing degranulation of histamine
increased mucus production
vasodilation
increasing pain
proinflammatory cytokines and leukotriene secretion

121
Q

What are type II hypersensitivity reactions mediated by?

A

IgG and IgM with opsonisation, complement activation and fc mediated activation of other immune cells such as NK cells

122
Q

What is a type III hypersensitivity reaction?

A

soluble immune complexes lodge in the capillaries between endothelial cells and basal membrane, promoting vasodilation and inflammation leading to tissue death and haemorrhage

123
Q

What are type IV hypersensitivity reactions?

A

Th1 cell releases cytokines that activate macrophages

124
Q

What are examples of hypersensitivity type IV reactions?

A

dermatitis and tubercular lesions/graft rejection

125
Q

what types of hypersensitivity are considered autoimmunity?

A

II, III and IV

126
Q

What is the rearrangement of the variable regions of BCRs called

A

VDJ recombination

127
Q

What is central tolerance?

A

T and B cells are exposed to self-antigens in the thymus and bone marrow and if reactive to sell they will get eliminated

128
Q

What is the role of Treg cells

A

CD4+ T cells that suppress the activity of self reactive T and B cells - dampen the immune response

129
Q

What are the suppressive cytokines released by Treg cells

A

IL-10 and TGFb

130
Q

What is the defect in IPEX syndrome?

A

mutation in FOXP3 causing a defect in Tregs resulting in a failure of peripheral tolerance

131
Q

What are the three types of HLA genes in MHC class I

A

HLA-A HLA-B and HLA-C

132
Q

What are the three types of HLA in MHC II

A

HLA-DR, HLA-DQ and HLA-DP (these come from separate alpha and beta proteins)

133
Q

Why do certain HLA genes increase your susceptibility to autoimmune diseases

A

Because it results in you having MHC or receptors that will bind and respond to self-peptides

134
Q

What is graves disease?

A

an autoimmune disease characterised by the overproduction of the T3 and T4 throid hormones causing hyperthyroidism

135
Q

What are four main environmental influences that can trigger autoimmunity?

A

infections
cigarette smoking
hormone levels
tissue damage - chronic inflammation for eg

136
Q

What mechanisms are used to influence an autoimmune disease?

A

molecular mimicry
alterations to self antigens
antigen sequestration
bacterial superantigens

137
Q

What is the term used when there are shared antigen epitopes causing antibodies to bind to proteins expressed on self organs

A

molecular mimicry

138
Q

Give an example where molecular mimicry is used in a disease

A

acute rheumatic fever where antibodies directed to destroy streptococcal (M5) cell walls can also cross-react in the heart tissue and bind to cardiac tissue proteins causing tissue damage

139
Q

What is antigenic sequestration

A

antigens that reside in hidden areas and do not come in contact with the immune system unless sometimes in injury or trauma

140
Q

What is meant by bacterial superantigens

A

toxins that can trigger an excessive reaction of the immune system (massive cytokine release and activation of T cells) - this is the case in toxic shock

141
Q

What are examples of autoimmune disease driven by type II hypersensitivity

A

autoimmune hemolytic anaemia
graves disease
myasthenia gravis
guillen barre syndrome
goodpastures syndrome

142
Q

SLE is caused by type IV hypersensitivity, true or false

A

false, it is caused by type III because of the presence of complement activation

143
Q

Name type III hypersensitivities

A

SLE
Rheumatoid arthritis
glomerylonephritis

144
Q

What is SLE

A

Systemic lupus erythematosus - here triggers such as excess UV radiation causing apoptosis of cells and the clearance by phagocytes is lacking causing an increased presence of self antigens resulting in increased T and B cell responses causing inflammation

145
Q

Examples of Type IV autoimmunities

A

multiple sclerosis
rheumatoid arthritis
diabetes mellitus
autoimmune myocarditis

146
Q

Autoimmune diseases can only be classified in one type of hypersensitivity, true or false?

A

false, they can involve a combination of these types of hypersensitivities

147
Q

What cells are present in the crypts?

A

goblet cells (mucus secreting) and intestinal stem cells

148
Q
A

Foundations in Medicine 1 (11 decks)

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