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Z Old Infection IGNORE > T Cell Responses to Viral Infection and Immunodeficiency > Flashcards

T Cell Responses to Viral Infection and Immunodeficiency Flashcards

1
Q

What are viruses?

A

Small, obligate intracellular parasites

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2
Q

How do viruses cause infection?

A

By invading cells of the body and multiplying within them

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3
Q

What do the anti-viral mechanisms of the immune system do?

A

To attack the virus in both the extracellular and intracellular phases of the viral life cycle

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4
Q

Are the effectors of the anti-viral mechanisms of the immune system specific or non-specific?

A

Can be either

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5
Q

What are the innate mechanisms in viral infections?

A
  • Type I interferons
  • Natural Killer cells
  • IFN-γ
  • Antiviral proteins
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6
Q

What are the classes of type I interferons?

A
  • α
  • ß
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7
Q

What produces type I interferons?

A

Many cell types

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8
Q

What are type I interferons produced in response to?

A

Viral infection

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9
Q

What do natural killer cells do?

A

Recognise and lyse virally infected cells

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10
Q

What produces IFN-γ?

A

Some activated CD4+ cells, CD8+ cells, and NK cells

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11
Q

What does IFN-γ cause?

A

Induction of an antiviral state in cells

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12
Q

What is the antiviral state in cells, induced by IFN-γ, characterised by?

A

Inhibition of viral replication and cell proliferation

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13
Q

Give two antiviral proteins

A
  • Defensins
  • APOCEC3Gs
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14
Q

What are the adaptive mechanisms in viral infections?

A
  • Neutralising antibodies
  • Cytotoxic T cells
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15
Q

What are NK cells?

A

A subset of lymphocytes found in the blood and tissues

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16
Q

Are NK cells T cells?

A

No

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17
Q

Why are NK cells not T cells?

A

Because they lack CD3 and have no antigen specific surface receptors (no IgRs or TcRs)

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18
Q

What ability to NK cells possess?

A

To recognise and lyse virally ifnected cells and (certain) tumour cells

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19
Q

What are the types of NK cell receptors?

A
  • MHC Class I receptor
  • Non self or stress antigens
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20
Q

What does the MHC Class I receptor do?

A
  • Delivers inhibitory signals to the NK cell
  • Recognises self
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21
Q

What do non self or stress signals do?

A

Stimulatory signal to NK cell, activating it

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22
Q

What is the outcome of NK cell interaction with a potential target cell determined by?

A

The balance of inhibtory and activating signals

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23
Q

What do many virally infected and cancer cells show?

A

Reduced express of MHC Class I

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24
Q

What is the result of many virally infected and cancer cells showing reduced expression of MHC Class I?

A

They are more susceptible to NK cell mediated lysis

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25
Q

Why are virally infected and cancer cells showing reduced expression of MHC Class I more susceptible to NK cell mediated lysis?

A

Due to the loss of inhibitory signals

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26
Q

What do activated NK cells do?

A
  • Lyse virally infected and tumour cells
  • Release IFN-γ
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27
Q

What is the result of the IFN-γ release from activated NK cells?

A

Promotes the cell mediated immune response at the site of infection

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28
Q

How long is the lag phase of clonal expansion for NK cells to become active as effectors?

A

None

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29
Q

What is the result of there being no lag phase for NK cells to become active as effectors?

A

NK cells may be early effectors in the course of viral infection

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30
Q

What are cytotoxic (CD8+) T cells?

A

The principle effector cells of the adaptive immune response to viral infectiosn

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31
Q

What do cytotoxic T cells recognise?

A

Specific viral antigens via their T cels receptors

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32
Q

How do cytotoxic T cells kill virally infected cells?

A

By inducing apoptosis

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33
Q

By what pathways to cytotoxic T cells induce apoptosis in virally infected cells?

A
  • T cell receptors interacting with MHC Class I
  • Fas-Fas ligand pathway
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34
Q

What is the main pathway by which cytotoxic T cells kill virally infected cells?

A

T cell receptors interacting with MHC Class I

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35
Q

What happens in the T cell receptors interacting with MHC Class I pathway?

A
  • Interaction induces the CD8+ cell to release cytotoxic granules
  • Granules contain Perforin, causing pore formation in the target cell
  • Granules also contain Granzymes, which enter through the pore and initiate apoptosis
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36
Q

What kind of molecules are Granzymes?

A

Serine proteases

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37
Q

What kind of molecules are Granzymes?

A

Serine proteases

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38
Q

What happens in the Fas-Fas ligand pathways of inducing apoptosis?

A
  • Activated CD8+ cells express Fas ligand
  • Binds and cross-links Fas on the surface of the target cell
  • Cross-linking of Fas sends apoptosis signals to the target cell
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39
Q

Do CD8+ cells recognise exogenous or endogenous antigens?

A

Endogenous

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40
Q

What is the result of CD8+ cells recognising endogenous antigens?

A

The induction of a CD8+ response requires de novo antigen synthesis

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41
Q

What is the result of the induction of CD8+ response requiring de novo antigen synthesis?

A

Killed vaccines are poor inducers of CD8+

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42
Q

What is the problem with CD8+ cells response?

A

Sometimes the damage done by the CD8 cells is greater than the damage done by the virus itself

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43
Q

Give an example of where the damage done by CD8+ is worse than the damage done by the virus itself

A

Fulminant hepatitis

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44
Q

What happens in fulminant hepatitis?

A

Virus-specific CD8 cell damage is greater than the damage caused by hepatitis B

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45
Q

What are the types of antibodies?

A
  • Neutralising antibody
  • Opsonising antibody
  • Antibody-directed cellular cytotoxicity
  • Virus specific antibodies
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46
Q

What is the most effective type of anti-viral antibody?

A

Neutralising antibody

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47
Q

What does a neutralising antibody do?

A

Binds to the virus

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48
Q

Where does a neutralising antibody bind to the virus?

A

Usually to the viral envelope or capsid proteins

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49
Q

What is the effect of neutralising antibodies binding to the virus?

A

Blocks the virus from binding and gaining entry to the host cell

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50
Q

What does an opsonising antibody do?

A
  • Enhances phagocytosis of virus particles
  • Complement activation by antibody-coated virus particles
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51
Q

What is antibody-directed cellular cytotoxicity dependant on?

A

Viral proteins expressed on the surface of infected cells

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52
Q

What happens in antibody-directed cellular cytotoxicity?

A

Subset of NK cells lyse the infected cell

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53
Q

What are the targets for virus specific antibodies?

A

Viral proteins expressed on the surface of the infected cell

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54
Q

Are all antibodies protective?

A

No

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55
Q

When may an antibody not be protective?

A

In certain cases, the antibody to the virus may facilitate its entry into a cell through Fc receptor-mediated uptake of the antibody-coated particle

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56
Q

What are antibodies that facilitate viral entry into the cell called?

A

Enhancing antibodies

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57
Q

How do CD4+ T lymphocytes contribute to the elimination of viruses?

A
  • Humoral response
  • Cell mediated response
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58
Q

What does the humoral response provide?

A

Help for the antibody response

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59
Q

What is the humoral reponse the main mechanism against?

A

Extracellular pathogens

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60
Q

What type of antibody is found in tissues in the humoral response?

A

IgG

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61
Q

What type of antibody is found at mucosal surfaces in the humoral response?

A

IgA

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62
Q

What type of antibody is produced in response to parasites in the humoral response?

A

IgE

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63
Q

What do CD4+ cells do in the humoral response?

A

Release cytokines that promote B cell growth, differentiation, antibody isotype switching and affinity maturation of the antibody response

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64
Q

What does an enhanced antibody response do in the humoral response?

A

Increases opsonisation, complement activation, neutralisation of toxins, and (in the caes of IgE) basophil/mast cell degranulation

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65
Q

What do CD4+ lymphocytes do in the cell mediated response against viruses?

A

Activates macrophages and/or cytotoxic T cells

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66
Q

What is the cell mediated response the main mechanism against?

A

Intracellular pathogens

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67
Q

What do CD4+ cells do in the cell mediated response?

A

Release cytokines that promote macrophage activation and/or cytotoxic T cell and NK cell activity

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68
Q

What can be activated depending on the types of infections?

A

Different T helper responses

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69
Q

What are different T helper responses activated depending on?

A

Polarising factors and specific profiles of cytokines that they release

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70
Q

What are the types of T helper cells?

A
  • Th1 helper T cells
  • Th2 helper T cells
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71
Q

What do Th1 helper cells release?

A

Predominantly IL-2, TNF, and IFN-γ

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72
Q

What do the cytokines released by Th1 helper T cells do?

A

Promote T cell proliferation, macrophage activation, enhance the cytolytic activity of CD8+/NK cells and the delayed hypersensitivity response

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73
Q

What promotes the Th1 response?

A

IL-12 release from APCs

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74
Q

What do Th2 helper T cells release?

A

Predominantly IL-4, IL-5 and IL-13

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75
Q

What do the cytokines released from Th2 helper T cells do?

A
  • Mediate antibody class switching towards IgA or IgE responses
  • Promote eosinophil recruitment
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76
Q

In what way do Th2 helper T cells skew a response?

A

Towards an ‘allergic type’

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77
Q

What promotes the Th2 response?

A

IL-4/IL-13 release from APCs

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78
Q

What is leprosy caused by?

A

Infection with Mycobacterium leprae

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79
Q

How does leprosy present clinically?

A

With a spectrum of disease, with the two extreme forms

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80
Q

What are the extreme forms of leprosy?

A
  • Tuberculoid
  • Lepromatous
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81
Q

What type of leprosy has more tissue damage?

A

Lepromatous

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82
Q

Which type of leprosy has more viable organisms?

A

Lepramatous

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83
Q

How does the body respond to a tuberculoid leprosy infection?

A

Strong, delayed type hypersensitivity response with T cell dependant granuloma formation

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84
Q

What is the result of the T cell dependant granuloma formation in tuberculoid leprosy?

A

Containment of the organism consisting of;

  • Activated macrophages
  • T cells
  • Epitheloid cells
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85
Q

What type of cytokine response is induced in tuberculoid leprosy?

A

Th1

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86
Q

What happens to the delayed type hypersensitivity response in lepramatous leprosy?

A

It is surpressed

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87
Q

What happens to the antibody levels in lepromatous leprosy?

A

They are raised, but do not control the infection

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88
Q

What kind of cytokine response is induced in lepromatous leprosy?

A

Th2

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89
Q

What is this micrograph showing?

A

Tuberculoid leprosy

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90
Q

What are the main features of tuberculoid leprosy?

A
  • Cellular immunity induced
  • Strong granuloma foramtion
  • Very few bacilli
  • Localised disease
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91
Q

What is this micrograph showing?

A

Lepromatous leprosy

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92
Q

What are the main features of lepromatous leprosy?

A
  • Humoral immunity induced
  • Poor granuloma formation
  • High bacilli load
  • Widespread disease
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93
Q

Is the Th1 or Th2 response favourable?

A

Usually Th1, however not always

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94
Q

When may a Th2 response be beneficial?

A

In certain parasitic infections

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95
Q

Give two parasitic infections where a Th2 response may be beneficial?

A
  • Nematodes
  • Flukes
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96
Q

Why may a Th2 response be beneficial in certain parasitic infections?

A

As the main effectors of the immune system that combat infecting organisms are IgE and Eosinophils

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97
Q

How do APC’s recognise various classes of microbe?

A

By Pathogen-Associated-Molecular-Patterns (PAMPs)

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98
Q

What are PAMPs?

A

The stuctures groups of pathogens share

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99
Q

What are the receptors that recognise PAMPs known as?

A

Pattern Recognition Receptors (PRRs)

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100
Q

Give two examples of PRRs

A
  • Toll-like receptors
  • Mannose receptors
101
Q

How do APCs help produce the most effective immunity to the organism?

A

They capture antigens from the site of infection and transport them to regional lymph nodes, where it instructs the antigen specific helper T cells as to the most appropriate cytokine response to produce effective immunity to the organism

102
Q

What is the PAMP for TLR2?

A

Peptioglycan

103
Q

What PAMP group is TLR2 in?

A

Gram +ve

104
Q

What is the PAMP for TLR3?

A

dsRNA

105
Q

What PAMP group is TLR3 in?

A

Viruses

106
Q

What is the PAMP for TLR4?

A

LPS

107
Q

What PAMP group is TLR4 in?

A

Gram -ve

108
Q

What is the PAMP for TLR5?

A

Flagellin

109
Q

What PAMP group is TLR5 in?

A

Bacteria

110
Q

What is the PAMP for TLR7?

A

ssDNA

111
Q

What PAMP group is TLR7 in?

A

Viruses

112
Q

What is the PAMP for TLR9?

A

dsDNA

113
Q

What PAMP group is TLR9 in?

A

Viruses

114
Q

Where are cytosolic pathogens degraded?

A

Cytoplasm

115
Q

What to cytosolic pathogen peptide bind to?

A

MHC Class I

116
Q

What are cytosolic pathogens presented to?

A

CD8 T cells

117
Q

What is the effect of cytosolic pathogens on the presenting cell?

A

Cell death

118
Q

Where are intravesicular pathogens degraded?

A

Acidified vesicles

119
Q

What do intravesicular pathogen peptides bind to?

A

MHC Class II

120
Q

What are intravesciular pathogens presented to?

A

CD4 T cells

121
Q

What is the effect of intravesicular pathogens of the presenting cell?

A

Activation to kill intravesicular bacteria and parasites

122
Q

Where are extracellular pathogens and toxins degraded?

A

Acidified vesicles

123
Q

What do extracellular pathogens and toxins peptides bind to?

A

MHC Class II

124
Q

What are extracellular pathogens and toxins presented to?

A

CD4 T cells

125
Q

What is the effect of extracellular pathogens and toxin on the presenting cell?

A

Activation of B cells to secrete Ig to eliminate extracellular bacteria/toxins

126
Q

What is meant by primary immunodeficiency?

A

Immunodeficiency that is due to an intrinsic defect of the cells or components of the immune system

127
Q

How is a primary immunodeficiency usually acquired?

A

Inherited

128
Q

What is meant by secondary immunodeficiency?

A

An immunodeficiency that is secondary to other disorders

129
Q

How is a secondary immunodeficiency usually controlled?

A

By treatment of the primary disease

130
Q

Is primary or secondary immunodeficiency more common?

A

Secondary

131
Q

When should immunodeficiency be suspected?

A

In any patient presenting with recurrent, severe, persistent or unusual infections

132
Q

What can be deficient in immunodeficiencies?

A
  • Antibody
  • Complement
  • Phagocytes
  • T cells
  • Combined B and T cells
133
Q

What types of infection result from antibody deficiencies?

A
  • Recurrent respiratory tract infections
  • Commonly encapsulated organisms
  • Streptococcus pneumoniae
  • Haemophilus influenza
  • Diarrhoea caused by Giarda lamblia
134
Q

What types of infections result from a complement deficiency?

A
  • Recurrent infection by encapsulated bacteria
  • Failure to clear immune complexes, leading to;
    • Glomerulonephritis
    • Systemic Lupus Erythematous (SLE)
135
Q

What types of infection result from phagocyte deficiencies?

A
  • Recurrent infections with bacteria, especially catalase +
  • Skin abscesses
    • Caused Staphylococcus aureus
  • Fungal infections
    • Aspergillus

​

136
Q

What types of infections result from T cell deficiencies?

A
  • Candida
  • Respiratory viruses
  • Pneumocystis carinii

Susceptible to basically any infection

137
Q

What types of infection result from combined T and B cell deficiencies?

A
  • Candida
  • Respiratory viruses
  • Pneumocystis carinii

Susceptible to basically any infection

138
Q

What can cause secondary immunodeficiencies?

A
  • Malnutrition
  • Drug-induced
  • Tumours
  • Infections
  • Loss of proteins/cells
  • Asplenia
  • Physiological
139
Q

What can cause malnutrition?

A
  • Famine
  • Drought
140
Q

What can cause drug-induced immunodeficiencies?

A
  • Immunosuppressive or cytotoxic therapy
  • Side effects from other drugs
141
Q

Give an example of a drug that has immunodeficiency side effects

A

Anti-epileptics

142
Q

What tumours can cause immunodeficiencies?

A
  • Lymphoproliferative disease/leukaemia
  • Non-haematological cancers
143
Q

What infection can cause immunodeficiencies?

A

HIV

144
Q

What can cause loss of protein/cells leading to immunodeficiencies?

A

Nephrotic syndrome

145
Q

What can cause asplenia?

A
  • Secondary to disease
  • Trauma
  • Surgery
146
Q

What disease can cause aspelnia?

A

Sickle cell anaemia

147
Q

What can cause physiological immunodeficiencies?

A
  • Age
  • Pregnancy
148
Q

What is the main target of the HIV/AIDS virus?

A

CD4+ helper cells

149
Q

What is the result of CD4+ helper cells being the main target of the HIV virus?

A

They are progressively lost from the circulation

150
Q

What happens as CD4+ count decreases in HIV?

A

Progressive immunodeficiency follows

151
Q

How is a HIV infection monitored?

A
  • Measuring the CD4+ cell count
  • Measuring the viral load
152
Q

What is HIV/AIDs commonly associated with?

A

Opportunistic infections such as Pneumocystis carinii pneumonia

153
Q

How can HIV/AIDs treated?

A

HAART

154
Q

What is the effect of HAART in the treatment of HIV/AIDs?

A

It can effectively reduce viral load and delay disease progression

155
Q

What is the problem with HAART in the treatment of HIV/AIDs?

A

It is expensive, and so not available to the majority of HIV-infected individuals worldwide

156
Q

What are asplenic patients particularly susceptible to?

A

Infections with encapsulated bacteria

157
Q

Why are asplenic patients particularly susceptible to infections with encapsulated bacteria?

A

Because they have an impaired antibody response to these organisms

158
Q

How should asplenia be managed?

A
  • Should be immunised against;
    • Pneumococci
    • Meningococci
    • Haemophilus influenza Type B
  • Should take broad-spectrum prophylactic antibiotic life
159
Q

What prophylactic antibiotic is usually given to asplenic patients?

A

Penicillin

160
Q

What are the types of primary immunodeficiencies?

A
  • Phagocytic cells
  • Complement deficiencies
  • Predominantly antibody deficiencies
  • Predominantly T cell or combined immunodeficiencies
161
Q

Give 3 diseases caused by a deficiency in phagocytic cells

A
  • Congenital Neutropenias
  • Chronic Granulomatous Disease
  • Leukocyte Adhesion Defect
162
Q

Give 2 examples of diseases caused by a complement deficiency

A
  • Complement component deficiency
  • Hereditary Angiodema
163
Q

Give two complement components that can be deficient

A
  • C3
  • MBL
164
Q

What is deficient in hereditary angiodema?

A

C1 inhibitor

165
Q

Give 6 diseases caused by predominantly antibody deficiencies

A
  • Transient hypogammaglobulinaemia of infancy
  • X-linked agammaglobulinaema (Bruton’s disease)
  • Common variable immunodeficiency
  • IgG subclass deficiency
  • IgA deficiency
  • Specific antibody deficiency
166
Q

Give 7 diseases caused by predominantly T cell or combined immunodeficiencies

A
  • Severe Combined Immunodeficiency (SCID)
  • Di George syndrome
  • X-linked lymphoproliferative disease (Duncan’s syndrome)
  • Type I cytokine/cytokine receptor deficiencies
  • MHC class I and class II deficiencies
  • X-linked hyper IgM syndrome (CD40 ligand deficiency)
  • Wiskott-Aldrich syndrome
167
Q

What is neutropaenia?

A

Low neutrophils

168
Q

What is agranulocytosis?

A

Complete absence of neutrophils

169
Q

What are the majority of cases of neutrophil deficincies due to?

A

A secondary deficiency

Primary deficiencies are rare

170
Q

What can cause a secondary neutrophil deficiency?

A
  • Leukaemia
  • Cytotoxic drugs
  • Autoantibodies
171
Q

How are primary neutrophil deficiencies acquired?

A

Inherited abnormalities

172
Q
A
173
Q

What can cause a primary neutrophil deficiency?

A
  • Leukocyte adhesion defect
  • Chronic Granulomatous Disease
174
Q

What causes a leukocyte adhesion defect?

A

Genetic deficiency of ß intergrin molecule CD18

175
Q

What is the effect of a leukocyte adhesion defect?

A

Affects phagocytes ability to migrate and phagocytose

176
Q

What causes Chronic Granulomatous Disease?

A

Gene defect affecting the phagocytes ability to produce a respiratory burst

177
Q

What is the effect of Chronic Granulomatous Disease?

A

No ROS, and so unable to kill phagocytosed organisms

178
Q

What is the inheritance pattern of chronic granulomatous disease?

A

X-linked and autosomal recessive variants

179
Q

What does the problems resulting from a complement component being missing in an individual depend on?

A

The pathway affected

180
Q

What pathways can be affected by a missing complement component?

A
  • Classical pathway
  • Lectin pathway
  • Alternate pathway
  • Membrane attack complex
181
Q

What can affect the classical pathway?

A

C1, C4, or C2 deficiency

182
Q

What is the effect of a deficiency affecting the classical pathway?

A

Recurrent infections by encapsulated bacteria

183
Q

Why does a deficiency in the classical pathway lead to recurrent infection by encapsulated bacteria?

A

Because removal requires the triad of antibody/complement/neutrophils

184
Q

What can affect the lectin pathway?

A

Deficiency of the mannose binding lectin (MBL)

185
Q

How common is a deficiency in the lectin pathway?

A

Relatively common

186
Q

What do problems with the lectin pathway lead to?

A

Recurrent miscarriage

187
Q

What can affect the alternate pathway?

A
  • Deficiency of Properdin
  • Deficiency of Factor D
188
Q

What does a Properdin deficiency lead to?

A

Bacterial meningitis

189
Q

What does a deficiency of Factor D lead to?

A

Recurrent respiratory tract infections

190
Q

How common are deficiencies affecting Factor D?

A

Relatively rare

191
Q

What do deficiencies of C3 cause?

A
  • Severe problems with recurrent infection, usually with pyogenic bacteria
  • Immune complex mediated disease
192
Q

Why are deficiencies of C3 important?

A

Because of the central position of C3 in complement pathways

193
Q

What can affect the membrane attack complex?

A

Deficiencies of C5, C6, C7, C8, and C9

194
Q

What is the effect of a deficiency affecting the membrane attack complex?

A
  • Recurrent infection with Neisseria
  • Recurrent meningococcal meningitis
195
Q

What is hereditary angiodema?

A

Deficiency of C1 inhibitor

196
Q

What is the inheritance pattern of hereditary angiodema?

A

Autosomal dominant

197
Q

Does hereditary angiodema cause increased susceptibility to infections?

A

No

198
Q

Why does a deficiency in C1 inhibitor lead to angiodema?

A

C1 inhibitor also inhibits proteins of the plasmin/kallikrein system. Lack of inhibition of these mediators leads to angiodema

199
Q

How does hereditary angiodema present?

A

Episodic swelling in subcutaneous and submucosal tissues

200
Q

How is hereditary angiodema treated?

A

Treat with infusions of C1 inhibitor or fresh frozen plasma

201
Q

What can an antibody deficiency be due to?

A
  • Secondary to diseases that supress B cell production by bone marrow
  • Loss of protein in certain conditions
202
Q

Give two diseases that suppress B cell production by the bone marrow

A
  • Lymphoma
  • Leukaemia
203
Q

What condition can lead to loss of protein?

A

Nephrotic syndrome

204
Q

When does primary antibody deficiency present?

A

Commonly presents in children, but may present at any age

205
Q

What does antibody deficiency form?

With regards to severity

A

A spectrum

206
Q

What is agammaglobulinaemia?

A

Absence of antibodies

207
Q

What is hypogammaglobulinaemia?

A

Low levels of antibodies

208
Q

Give 4 types of antibody deficiency

A
  • X-linked agammaglobulinaemia
  • Common variable immunodeficiency
  • IgG Subclass deficiency
  • IgA Deficiency
209
Q

What is X-linked agammaglobulinaemia?

A

A defect in tyrosine kinase

210
Q

What is the result of X-linked agammaglobulinaemia?

A

Absence of mature B cells

211
Q

What happens in common variable immunodeficiency?

A

B cells are present, but do not differentiate normally into plasma cells

212
Q

Where is the defect throught to be located in common variable immnodeficiency?

A

In helper T cells

213
Q

What is IgG subclass deficiency?

A

Failure to produce one or more subclass of IgG

214
Q

What subclass of IgG is most commonly failed to produce in IgG subclass deficiency?

A

IgG2

215
Q

What is the most common primary antibody deficiency?

A

IgA deficiency

216
Q

How may caucasians have IgA deficiency?

A

1 in 700

217
Q

How does IgA deficiency present?

A
  • Mainly asymptomatic
  • May have increased infections at mucosal sites
218
Q

What is IgA deficiency associated with?

A

Allergic and autoimmune disease

219
Q

What should be done in any patient with a known or suspected T cell immunodeficiency?

A
  • Live vaccines should be avoided
  • Blood products, if used, should be irradicated and screened as CMV negative
220
Q

Give 6 T cell deficiency diseases

A
  • Di George Syndrome
  • Wiskott-Aldrich Syndrome
  • X-linked hyper IgM syndrome
  • Severe Combined Immunodeficiency (SCID)
  • X-linked SCID
  • ADA/PNP SCID
221
Q

What is Di George Syndrome?

A

Failure of the thymus gland to develop

222
Q

How severe is Di George syndrome?

A

Severity varies

In complete Di George syndrome there is a virtual absence of T cells

223
Q

What is Wiskott-Aldrich Syndrome characterised by?

A
  • Eczama
  • Thrombocytopenia
  • T and B cell dysfunction
224
Q

What is X-linked hyper IgM syndrome?

A

T cell defect affecting antibody production and cell mediated immunity

225
Q

What is impaired in SCID?

A

Both cell mediated and humoral immunity

226
Q

When does SCID present?

A

In the first few months of life

227
Q

How does SCID present?

A
  • Failure to thrive
  • Infection
  • Diarrhoea
  • Hepatosplenomegaly
228
Q

What are almost all cases of SCID associated with?

A

Lymphopenia

229
Q

Why are almost all cases of SCID associated with lymphopenia?

A

Due to the failure of T cells (and in some cases variants NK and B cells as well) to develop

230
Q

At what level do T cells circulate in most cases of SCID?

A

Virtual absence

231
Q

What is the treatment for SCID?

A

Bone marrow transplantation

232
Q

What causes X-linked SCID?

A

Mutation in the gamma chain of the IL-2 receptor

233
Q

What happens in X-linked SCID?

A

Immature T cells cannot respond to IL-2, and fail to mature

234
Q

What is ADA SCID?

A

Adenosine Deaminase (ADA) Deficiency

235
Q

What is PNP SCID?

A

Purine Nucleotide Phosphorylate (PNP) Deficiency

236
Q

Why does ADA/PNP cause SCID?

A

Because developing T-cells are sensitive to the toxic metabolites that build up in the cell in the absence of these enzymes

237
Q

What is the first line investigation into phagocyte function?

A

Full blood count - WBC numbers

238
Q

What is the second line investigation into phagocyte function?

A

Neutrophil respiratory burst test

239
Q

What is the specialist investigation into phagocyte function

A
  • Chemotaxis
  • Pathogen killing
240
Q

What is the first line investigation into complement function?

A

Looking at C3, C4

241
Q

What is the second line investigation into complement function?

A

Looking at CH50 and AP50

242
Q

What is the specialist investigation of complement function?

A

Looking at individual complement components

243
Q

What is the first line investigation into antibody function?

A

Serum Igs and electrophoresis

244
Q

What is the second line investigation into antibody function?

A

Looking at IgG subclasses and specific antibodies

245
Q

What is the specialist investigation into antibody function?

A

Response to immunisation

246
Q

What is the first line investigation into cell mediated immunity function?

A

Full blood count - Lymphocyte numbers

247
Q

What is the second line investigation into cell mediated immunity function?

A

Immunophenotyping - Lymphocyte markers

248
Q

What is the specialist investigation into cell mediated immunity function?

A

Lymphocyte function test

Z Old Infection IGNORE (23 decks)

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