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2.1 Molecular Immunology > Sara- Primary Immunodeficiency > Flashcards

Sara- Primary Immunodeficiency Flashcards

(65 cards)

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1
Q

What cause primary immunodeficiencies?

A

Inherited defects in genes for components of the immune system

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2
Q

What are primary immunodeficiencies

A

Diseases usually revealed in early childhood due to enhanced susceptibility to infection

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3
Q

What are secondary immunodeficiencies?
(2)

A

Diseases caused by environmental factors

e.g. caused by infections or immunosuppressive drugs

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4
Q

Give an example of a primary immunodeficiency

A

X-Linked agammaglobulinemia

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5
Q

Give an example of a secondary immunodeficiency

A

Acquired Immunodeficiency Syndrome (AIDS) -> caused by HIV

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6
Q

List the causes of secondary immunodeficiency
(7)

A

Malnutrition

Diseases e.g. HIV

Genetic and metabolic diseases

Immunosuppressive drugs

Surgery and trauma splenectomy

Age extremes: prematurity and old age

Environmental stress

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7
Q

How does malnutrition cause secondary immunodeficiency

A

Clinical obesity has negative effects on natural killer cells

Lack of NK activity -> increased viral infections and cancer in clinically obese

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8
Q

Give an example of an environmental stress that causes secondary immunodeficiency

A

Cigarette smoking

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9
Q

How can surgery and trauma cause secondary immunodeficiency?
(3)

A

Splenectomy

B cell populations lost

Knock on effects

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10
Q

What are the ten warning signs of primary immunodeficiency (will come up on the exam)

A

Four or more new ear infections within one year

Two or more serious sinus infections within one year

Two or more months on antibiotics with little effect

Two or more pneumonias within one year

Failure of an infant to gain weight or grow normally

Recurrent, deep skin or organ abscesses

Persistent thrush in mouth or fungal infections on skin

Need for intravenous antibiotics to clear infections

Two or more deep-seated infections including speticemia

A family history of primary immunodeficiency

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11
Q

How have primary immunodeficiencies facilitated our understanding of how the immune system functions?

A

By highlighting the effects of the absences of particular proteins

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12
Q

What causes most PIDs

A

Caused by mutant genes that confer no selective advantage to the individuals that carry them

They vary in severity from mild to fatal if the defect is not corrected or the infections are not prevented

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13
Q

List the different categories of primary immunodeficiency
(6)

A

Antibody deficiencies

Combined cellular and antibody deficiencies

Cellular deficiencies

Phagocytic cell deficiencies

Complement deficiencies

Very rare -> immune regulation deficiency (AIRE defect)

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14
Q

What are CIDs

A

Combined Immunodeficiencies

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15
Q

Write a note on combined immunodeficiencies
(3)

A

Among the most severe PIDs

Result from an absence of T cells, or impaired T cell function, combined with some disruption of antibody response

No T helper cells needed for B cell activation -> no antibody production

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16
Q

What causes CID
(3)

A

Absence of T cells

Impaired T cell function

Combined with some disruption of antibody response

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17
Q

What does a T cell deficiency do?
(3)

A

Results in no B cell activation

Results in no antibody class switching

Reduction in cell mediated cytotoxicity, therefore an increase in viral, protozoal, fungal and mycobacterial infections is observed

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18
Q

Write about SCID

A

The most extreme forms of CID

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19
Q

What gene defects can cause CID?
(5)

A

CD3 chains

Mitochondrial adenylate kinase

RAG1 and RAG2 or Artemis

Common y chain and JAK3

Adenosine deaminase (ADA) or purine nucleoside phosphorylase (PNP)

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20
Q

What do defects in adenosine deaminase or purine nucleoside phosphorylase do?
(3)

A

Nucleotide metabolites accumulate

These are particularly toxic to developing T cells and less so to developing B cells

Autosomally inherited

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21
Q

What does ADA stand for?

A

Adenosine deaminase

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22
Q

What does PNP stand for?

A

Purine nucleoside phosphorylase

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23
Q

Write about common y chain and JAK3 and how they cause SCID

A

Common y chain is X linked

JAK3 is autosomally inherited

Lack of signalling or signal transduction

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24
Q

Write about RAD1 and RAG2 or Artemis

A

No T cell receptors

No Antibody production

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25
Write about CD3 chains and how they cause SCID
No T cell receptor complex expression for signalling
26
Write about mitochondrial adenylate kinase and how they cause SCID
Defective differentiation of myeloid and lymphoid lineages from stem cells Reticular dysgenesis
27
What are antibody deficiencies?
A diverse spectrum of diseases Ranges from the complete absence of mature recirculating B cells, plasma cells and Abs to the selective absence of certain classes of Abs e.g. IgA deficiency Patients with these inherited deficiencies usually experience recurrent bacterial infection (caused by encapsulated bacteria) but have normal immunity to most viral and fungal infections
28
What happens to patients with antibody deficiencies? (2)
Experience recurrent bacterial infection (caused by encapsulated bacteria) Have normal immunity to most viral and fungal infections
29
Describe the different types of antibody deficiencies
Ranges from the complete absence of mature recirculating B cells, plasma cells and Abs to the selective absence of certain classes of Abs e.g. IgA deficiency
30
Write a note on X-Linked Agammaglobulinemia (6)
Originally called Bruton's agammaglobulinemia Patients have extremely low Ab levels Babies born with this have virtually no B cells in peripheral blood Suffer from recurrent bacterial infections It is caused by a defect in the gene coding for the enzyme Bruton's tyrosine kinase (Btk) which is involved in B cell development Developing cells in the basal membrane are arrested at the pre-BCR stage
31
What is X-Linked Agammaglobulinemia originally called
Bruton's agammaglobulinemia
32
What are the characteristics of XLA (3)
Extremely low Ab levels Babies have virtually no B cells in their peripheral blood Suffer from recurrent bacterial infections
33
What causes XLA? (3)
A defect in the gene coding for the enzyme Bruton's tyrosine kinase (Btk) This enzyme is involved in B cell development Developing cells in the BM are arrested at he pre-BCR stage
34
Write a note on phagocytic deficiencies (3)
PIDs which result in depressed numbers of phagocytic cells or faulty cell motility, adherence, phagocytosis and intracellular killing of microorganisms Phagocytosis mediated by macrophages and neutrophils is the principle way the immune system gets rid of infecting bacteria and other microbes Any defect that compromises phagocyte activity had profound effects on the immune system's capacity to clear infection
35
What are the characteristics of phagocytic deficiencies (5)
Depressed numbers of phagocytic cells Faulty cell motility Faulty adherence Faulty phagocytosis Faulty intracellular killing of microorganisms
36
Write a note on leucocyte adhesion deficiency (4)
LADI is caused by a mutation in the CD18 gene CD18 is the B chain of B2 integrins that include CR3. CR4 and LFA-1, all vital for the adhesion cascade As CR3 and CR4 also function in the complement system phagocytes are unable to engulf microbes opsonised by C3b and C4b Patients display omphalitis, gingivitis and recurrent infections
37
What causes LADI
A mutation in the CD18 gene
38
What is CD18 (3)
CD18 is the B chain of B2 integrins including, CR3, CR4 and LFA-1 All of these are vital for the adhesion cascade
39
What does loss of CR3 and CR4 do? (2)
CR3 and CR4 play a role in the complement system Phagocytes are unable to engulf microbes opsonised by C3b and C4b
40
List some symptoms of LAD1 (3)
Patients display omphalitis Gingivitis Recurrent infections
41
What does a C3 deficiency do
Susceptibility to a wide range of pyogenic infections
42
What does a C5-C9 and properdin deficiency do?
Susceptibility to Neisseria
43
What does a C1, 2 and 4 deficiency do?
Immune complex disease
44
What does MBL deficiency do
Increased susceptibility to bacterial and fungal infections
45
What does DAF or CD59 deficiency do
Autoimmunity Paroxysmal nocturnal haemoglobinuria - erythrocytes are destroyed
46
What does C1 inhibitor deficiency do?
Hereditary angioedema (HAE) Bouts of swelling of the face, larynx and abdomen The classical pathway is overactive - low C2 and C4 and raised C2a (vasoactive component)
47
What is the role of the clinical immunology laboratory in the diagnosis of primary immunodeficiency (6)
Detection of autoantibodies -> ELISA, immunofluorescence (direct and indirect) Measurement of antibody levels - nephelometry Measurement of specific antibody responses Monitoring of serum proteins via serum protein electrophoresis Measurement of complement levels/function - nephelometry, CH50, CH100 and AP50 assays Leukocyte number/functions - flow cytometry
48
Why would we measure specific antibody responses
Response to vaccination IgE to allergens
49
Why would we monitor serum proteins via serum protein electrophoresis?
Detection/characterisation of monoclonal gammopathy (SPE/IFE) Detection of XLA via SPE
50
List the methods of measurement of complement levels
Nephelometry CH50 assays CH100 assays AP50 assays
51
List the methods of measurement of leukocyte number/functions
Flow cytometry
52
What are the principles of nephelometry (3)
Add anti-sera for protein of interest (e.g. antibodies, C3, C4 and C1 inhibitor) Where immune complexes form they will scatter light which can be detected Standards can be used to calculate the concentration
53
Nephelometry is used to detect what proteins
Antibodies C3 C4 C1 inhibitor
54
Name two brands of nephelometers
Roche COBAS 6000 Binding Site OPTILITE
55
What is the principle of serum protein electrophoresis? (3)
Electrophoresis is a method of separating proteins based on their physical properties Serum is placed on a specific medium, and a charge is applied The net charge (positive or negative) and the size and shape of the protein are used to separate and differentiate the various serum proteins
56
Give an example of a machine for SPE
SEBIA Hydrasys SPE system
57
List the different tests of the complement system (2)
Haemolysis assays Measurement of levels of complement components
58
List the different types of haemolysis assays (2)
CH50 and CH100 -> assays of the classical pathway Ah50 - assay of the alternative pathway
59
How are levels of complement components measured?
Measured via nephelometry
60
What levels of complement components are measured via nephelometry
C3 C4 C1 inhibitor
61
What is the principle of flow cytometry?
Flow cytometry is a technique for counting, examining and sorting microscopic particles suspended in a stream of fluid Physical characteristics, size and granularity of particles are measured while fluorescently labelled antibodies can be used to examine protein expression A laser beam is directed at a hydro-dynamically focused stream of fluid containing the cells in single cell suspension A number of detectors measure properties such as forward scatter(size), side scatter (granularity) and fluorescence (specific protein expression) at different wavelengths
62
What is measured via flow cytometry (3)
Forward scatter(size) Side scatter (granularity) Fluorescence (specific protein expression)
63
Give an example of a flow cytometer
FASCANTO II
64
Flow cytometry is used in the diagnosis of what? (4)
SCID XLA CGD LADI
65
What does SCID stand for?
Severe combined immunodeficiency

2.1 Molecular Immunology (19 decks)

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