Immunology 2 - Primary immune deficiencies parts 1 & 2 Flashcards Preview

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Flashcards in Immunology 2 - Primary immune deficiencies parts 1 & 2 Deck (77)
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1
Q

Recall 3 infections that can cause immunodeficiency

A

HIV
Measles virus
Mycobacterial infection

2
Q

Recall 3 diseases of neutrophil deficiency

A

Reticular dysgenesis
Kostmann syndrome
Cyclic neutropenia

3
Q

What is the cause of Leukocyte adhesion deficiency?

A

CD18 deficiency - failure to express this ligand means they cannot exit the bloodstream

4
Q

What will be the most obvious abnormal result on the blood count in leukocyte adhesion deficiency?

A

Very high neutrophils (they cannot exit the bloodstream)

5
Q

What is chronic granulomatous disease?

A

A failure of phagocytic oxidative killing mechanisms

6
Q

Recall 2 tests that are useful in the investigation of chronic granulomatous disease

A
  1. Nitroblue tetrazolium test (negative = blue, positive = yellow)
  2. Dihydrohodamine flow cytometry test (negative = fluorescent)
7
Q

Which innate immunodeficiency is characterised by severe chickenpox and disseminated CMV infection?

A

Classic Natural Killer cell deficiency

8
Q

Which innate immunodeficiency is characterised by recurrent infections with hepatosplenomegaly and abnormal dihydrohodamine test (does not fluoresce)?

A

Chronic granulomatous disease

9
Q

Which innate immunodeficiency is characterised by recurrent infections with no neutrophils on FBC?

A

Kostmann syndrome

10
Q

Which innate immunodeficiency is characterised by infection with atypical mycobacterium, and a normal FBC?

A

IFN gamma receptor deficiency

11
Q

Which innate immunodeficiency is characterised by recurrent infections with high neutrophil count on FBC but no abscess formation?

A

Leukocyte adhesion deficiency

12
Q

With which innate immunity deficiency is meningococcal septicaemia associated?

A

Deficiency of complement (C1q)

13
Q

With which innate immunodeficiency is membranoproliferative nephritis and abnormal fat distribution associated?

A

C3 deficiency with presence of a nephritic factor

14
Q

What mutation is causative of X-linked SCID?

A

Common gamma chain on chromosome Xq13.1

15
Q

Describe the phenotype of X-linked SCID in terms of T, B and NK cell numbers

A

T cells: very low or absent

B cells: Normal or increased B cells, but LOW Igs

NK cells: very low or absent

16
Q

How does adenosine deaminase deficiency affect the immune system?

A

This enzyme is necessary for cell metabolism in lymphocytes.

When it is deficient, there is early arrest of T and NK cell development and production of immature B cells.

17
Q

Describe the phenotype of ADA deficiency in terms of T, B and NK cell numbers

A

All very low or absent

18
Q

Describe the clinical phenotype of SCID

A
  1. Unwell by 3 months of age
  2. Infections of all types
  3. Failure to thrive
  4. Persistent diarrhoea
  5. Unusual skin disease
  6. Family history of early infant death
19
Q

What is the gene mutation implicated in DiGeorge syndrome?

A

22q11.2 deletion

20
Q

How does DiGeorge syndrome affect B and T cell levels?

A

Normal B cells

Reduce T cells

21
Q

What is bare lymphocyte syndrome type 2?

A

Absent expression of MHC class II causing severe deficiency of CD4+ T helper cells –> results in low IgG OR IgA

22
Q

What inherited immunodeficiency might cause a profound deficiency of CD4+ T cells specifically?

A

Bare lymphcoyte syndrome type 2

23
Q

What is reticular dysgenesis?

A

Failure of stem cells in BM to differentiate along myeloid or lymphoid lineage

24
Q

What is Kostmann syndrome?

A

Failure of neutrophils to mature - causes a congenital neutropenia

25
Q

What is cyclic neutropaenia?

A

Autosomal dominant episodic neutropenia every 4-6 weeks

26
Q

What are the features of chronic granulomatous disease?

A

Absent respiratory burst, leading to:

  • Excessive inflammation
  • Granuloma formation
  • Lymphadenopathy
  • Hepatosplenomegaly
27
Q

What immunodeficiency are recurrent skin and mouth infections most likely to be indicative of?

A

Phagocyte deficiency

28
Q

Which phagocyte deficiency has absent neutrophils and normal leukocyte adhesion molecules?

A

Kostmann syndrome

29
Q

Which phagocyte deficiency has absent CD18 and increased neutrophils?

A

Leukocyte adhesion deficiency

30
Q

Which phagocyte deficiency has normal neutrophil levels and leukocyte adhesion markers, an abormal NBT/DHR test and pus is produced?

A

Chronic granulomatous disease

31
Q

Which phagocyte deficiency has normal neutrophil levels and leukocyte adhesion markers, a normal NBT/DHR test but no pus is produced?

A

Cytokine deficiency (IL12/IFN gamma pathway)

32
Q

Describe the classical pathway of complement activation

A

Antibody-antigen complex (involves C1,C3,C4)

33
Q

Describe the MBL pathway of complement activation

A

Activation of complement by the direct binding of MBL to microbial cell surface carbohydrates

34
Q

Describe the alternate pathway of complement activation

A

Involves bacterial cell wall

35
Q

Name 3 encapsulated bacteria

A

NHS
Neisseria meningitides
Haemophilus influennzae
Streptococcus pneumoniae

36
Q

What does classical complement pathway deficiency increase susceptibility to?

A

SLE

37
Q

Susceptibility to encapsulated bacteria may be indicative of what type of immunodeficiency?

A

Complement deficiency

38
Q

How does SLE affect complement?

A

Persistent production of immune complexes –> activation of classical pathway –> low levels of C3 and C4 (functional complement deficiency)

39
Q

What are the standard tests in suspected complement deficiency?

A

C3
C4
CH50
AP50

40
Q

What does CH50 measure?

A

Classical complement pathway

41
Q

What does AP50 measure?

A

Alternative complement pathway

42
Q

Which complement function test would be abnormal in C1q deficiency?

A

CH50

43
Q

Which tests would be abornmal in C9 deficiency?

A

CH50 and AP50

44
Q

Which complement deficiency is most associated with developmental SLE?

A

C1q deficiency

45
Q

In which complement pathway is properdin found?

A

Alternative

46
Q

Which complement deficiency is most associated with meningococcal disease?

A

C7 deficiency

47
Q

How do phagocytes detect pathogens at the site of infection?

A

Expression of genetically-coded receptors such as toll-like receptors, which detect PAMPs

48
Q

What type of B cells produce IgM?

A

Pro B cells

49
Q

What is the most severe form of SCID?

A

Reticular dysgenesis

50
Q

What is the most common form of SCID?

A

X-linked SCID

51
Q

Why are SCID babies initially protected?

A

IgG of mother

52
Q

Why does Di George syndrome produce immunodeficiency?

A

Abnormality of development of pharyngeal pouch –> absent thymus

53
Q

What test can be used to see lymphocyte subsets in a blood sample?

A

FACS (flow cytometry)

54
Q

What is Bruton’s X-linked hypogammaglobinaemia?

A

Abnormality in B cell tyrosine kinase gene: Pre B cells don’t mature so no Ig after around 3 months
Only affects boys

55
Q

What is the inheritance pattern of hyper IgM syndrome?

A

X linked

56
Q

What is hyper IgM syndrome?

A

B cell maturation defect which results in T cells not expressing CD40 (Failure of T cell co-stimulation)

57
Q

In which disease is CD40 not expressed on activated T cells?

A

Hyper IgM syndrome

58
Q

Which syndrome is characterised by elevated IgM and undetectable IgA, IgE and IgG?

A

Hyper IgM syndrome

59
Q

Which disease is marked by reduction in IgG with low either IgA/IgM

A

Common variable immune deficiency

60
Q

What are the clinical features of common variable immune deficiency?

A

Recurrent bacterial infections
Pulmonary disease (in particular granulomatous interstitial lung disease)
GI disease

61
Q

What % of Selective IgA deficiency patients are symptomatic, and what are these symptoms?

A

1/3

Recurrent GI and resp infections

62
Q

How are B cell deficiencies managed?

A

Lifelong immunoglobulin replacement

63
Q

Recall the levels of T, B and NK cells in ADA deficiency

A

All very low or absent

64
Q

What mutation causes reticular dysgenesis?

A

Adenylate kinase 2 (AKA2) - a mitochondrial energy enzyme

65
Q

What mutation causes kostmann syndrome?

A

HCLS1-associated protein X-1 (HAX-1)

66
Q

What mutation causes cyclic neutropaenia?

A

Neutrophil elastase (ELA-2)

67
Q

What can be used to treat chronic granulomatous disease?

A

Interferon gamma (as this stimulates macrophages)

68
Q

What are the symptoms of DiGeorge syndrome?

A
CATCH 22
Cardiac abnormalities (especially ToF) 
Abnormal facies (low set ears) 
Thymic aplasia 
Cleft palate
Hypoalcaemia/hypoPTHism
Chromosome 22
69
Q

Recall some clinical signs of bare lymphocyte syndrome

A

Hepatomegaly and jaundice

May be associated with sclerosing cholangitis

70
Q

What is the inheritance pattern of Wiskott-Aldrich Syndrome?

A

X linked recessive

71
Q

What mutation causes Wiskott-Aldrich Syndrome?

A

WASP gene mutation (actin cytoskeleton rearrangement which is needed to stabilise T cell-APC interaction)

72
Q

Which immunodeficiency might cause a low IgM with raised IgA and IgE?

A

Wiskott-Aldrich Syndrome

73
Q

What comborbidity does Wiskott-Aldrich Syndrome put you at risk of?

A

Malignant lymphoma

74
Q

What is the prevelance of selective IgA deficiency?

A

1:600

75
Q

Recall 3 clinical features of hyper IgM syndrome

A

Pneumocystis jiroveci infection
Autoimmune disease
Malignancy

76
Q

At what age does common variable immune deficiency present?

A

Adulthood

77
Q

Which mutation is most likely to be the cause of CVID?

A

MHC class III - causing aberrant class switching

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