Immunodeficiencies Flashcards

1
Q

What are immunodeficiencies caused by?

A

Defects in one or more components of the immune system

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2
Q

What are the types of immunodeficiencies?

A

Primary (congenital)

Secondary

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3
Q

What do primary immunodeficiencies result from?

A

Genetic or developmental defects

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4
Q

When do primary immunodeficiencies originate and present?

A

There from birth but may not be clinically observed till later in life

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5
Q

What do secondary immunodeficiencies originate as a result of?

A

Malnutrition, cancer, drug treatment or infection

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6
Q

What’s the most common secondary immunodeficiency?

A

AIDS

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7
Q

What are clinical features of primary immunodeficiencies?

A

Recurrent infections

Severe infections by unusual pathogens in unusual sites

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8
Q

What are the causes of primary immunodeficiencies?

A

Defect in phagocytic or complement function

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9
Q

What do consequences of primary immunodeficiency depend on?

A

The number and type of immune system components involved

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10
Q

What do defects in earlier stem cells affect?

A

The entire immune system

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11
Q

What do defects in later stage haematopoietic cells show?

A

A more restricted pathology

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12
Q

What are examples of phagocytic disease?

A

Chronic granulomatous disease
Congenital agranulocytosis
Leukocyte-adhesion deficiency

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13
Q

What are examples of B cell and antibody diseases?

A

X-linked agammaglobulinaemia
Common variable hypogammaglobulinaemia
X-linked hyper-IgM syndrome
Selective immunoglobulin deficiency c

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14
Q

What is an example of a thymic epithelial cell mediated disease?

A

Digeorge syndrome

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15
Q

What are examples of combined B and T cell diseases?

A

Reticular dysgenesis
Severe combined immunodeficiency
Bare-lymphocyte syndrome
Wiskott-Aldrich syndrome

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16
Q

What is affected in primary component disorders?

A

Defects in lymphocyte development or activation

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17
Q

What causes X-linked agammaglobulinaemia?

A

Encodes brutons tyrosine kinase

Block in B cell development at pre-b stage

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18
Q

What are the clinical features of x-linked agammaglobulinaemia?

A

Absence of B cells and low/absent plasma cells
All IgGs absent/very low
T cells and T cell mediated response normal

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19
Q

How is x-linked agammaglobulinaemia treated?

A

IVIg at 2-3 week intervals
Or subcutaneous Ig weekly
Prompt antibiotic therapy

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20
Q

What is common variable immunodeficiency?

A

Selective IgA deficiencies

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21
Q

What are the symptoms of common variable immunodeficiency?

A

Mainly asymptomatic- some lead to respiratory, urogenital or GI infections

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22
Q

What are the lab findings with common variable immunodeficiency?

A

Low serum and secretory IgA

23
Q

What are the causes of Severe combined immunodeficiency?

A

Defect in common cytokine receptor gamma chain

24
Q

What is IL-7 needed for?

A

Survival of T cell precursors

25
Q

What happens if you have defective IL-7?

A

Defective T cell development and concomitant lack in B cell help

26
Q

What does a defect in RAG1/RAG2 lead to?

A

No T or B cells

27
Q

What happens in adenosine Deaminase deficiency?

A

Accumulation of deoxyadenosine and deoxy-ATP which is toxic for rapidly dividing thymocytes

28
Q

What are the lab signs of severe combined immunodeficiency?

A

Very low/absent T cell
Normal/absent B cell
Sometimes absent NK
Low Ig

29
Q

What are the treatments for severe combined immunodeficiency?

A
No live vaccines
IVIg replacement
Infection prophylaxis
Bone marrow/haematopoietic stem cell transplant 
Gene therapy
30
Q

What are the survival rates for severe combined immunodeficiency?

A

High if early diagnosis and a good donor match with no infections pre-transplant

Low if late diagnosis and poor donor match with chronic infections

31
Q

What is the treatment of di george syndrome?

A

Thymus transplantation

32
Q

What does digeorge syndrome result in?

A

Failure of development of 3rd and 4th pharyngeal pouches

33
Q

What are the symptoms of digeorge?

A

Dysmorphic face
Hypocalcaemia
Cardiac abnormalities
Variable immunodeficiency

34
Q

What are the dysmorphic features of digeorge?

A

Cleft palate, low set ears, fish shaped mouth

35
Q

What causes Wiskott-Aldrich syndrome?

A

Defect in WASP

36
Q

What is WASP?

A

Protein involved in actin polymerisation

37
Q

What does Wiskott-Aldrich syndrome cause?

A

Thrombocytopenia, eczema, infections

Progressive immunodeficiency

38
Q

What are the two types of phagocyte defects?

A

Quantitative

Qualitative

39
Q

What do quantitative phagocyte defects cause?

A

Low phagocyte numbers

40
Q

What do qualitative phagocyte defects cause?

A

Altered function

41
Q

What are some types of recruitment defects?

A

Transmigration defects

42
Q

What are the types of innate immune system defects?

A

Phagocyte defects
Recruitment defects
Complement defects

43
Q

What are some examples of innate immune system defects?

A

Chronic granulomatous disease
Chediak higashi syndrome
Leukocyte adhesion deficiency

44
Q

What does chronic granulomatous disease cause?

A

Formation of granulomas

45
Q

What causes chronic granulomatous disease?

A

Defective oxidative killing of phagocytosed microbes due to a mutation in phagocyte oxidase components

46
Q

How do you diagnose chronic granulomatous disease?

A

Nitro blue tetrazolium reduction test

47
Q

What causes Chediak higashi syndrome?

A

Defect in LYST gene

48
Q

What are the lab signs of Chediak higashi syndrome?

A

Decreased number of neutrophils

49
Q

What are the symptoms of Chediak higashi syndrome?

A

Repetitive severe infections

50
Q

What are the mechanisms of leukocyte adhesion deficiency?

A

Defect in beta2-chain integrins
Defect in sialyl-Lewis X
Delayed umbilical cord separation -> diagnosis defect in beta2-chain integrins

51
Q

How does leukocyte adhesion deficiency present?

A

Skin, GIT infections and perianal ulcers

52
Q

What are the lab features of leukocyte adhesion deficiency?

A

Low neutrophil chemotaxis

Low integrin expression on phagocytes

53
Q

What are the treatment aims of primary immunodeficiencies?

A
Minimise/control infection
Prompt infection treatment
Prevention of infection 
Nutrition
Replace defective/absent component of the immune system