Immuno 4: Primary Immune Deficiencies 2 Flashcards

1
Q

What is the most common form of SCID ?

A

X-linked SCID

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2
Q

Which cells are affected in X-linked SCID and why ?

A

Reduction in T and NK cells
Increase in premature B cells

Because Common gamma chain is mutated which is an important component of Cytokine receptors. Therefore cant respond to cytokines causing early cell arrest in T and NK cells. No IgA or IgG because CD4+ Th cells needed for Isotype switching.

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3
Q

Which cells are affected in ADA deficiency SCID and why ?

A

Low T, NK and B cells

Adenosine deaminase enzyme is deficient which causes failure of lymphocyte maturation

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4
Q

Why are infants with SCID protected in the first 3 months ?

A

maternal IgG is still present in the infants circulation and provides immunity

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5
Q

What is the function of CD4+ T cells in the immune response ?

A
  • activates B cells

- activates CD8+ cytotoxic T cells

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6
Q

Which genetic syndrome causes the thymus to be underdeveloped and therefore a reduced number of T cells in children?

A

DiGeorge syndrome

T cell numbers recover with age

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7
Q

List 4 pathologies of DiGeorge syndrome ?

A

CATCH 22

Cardiac abnormalities ( Tetralogy of fallot)
Abnormal facies (low set ears, high forehead)
Thymic aplasia (Reduced T cells)
Cleft palate
Hypocalcaemia (hypoparathyroidism)

22nd chromosome mutation 22q11

(There is developmental defect in the pharyngeal pouch)

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8
Q

What causes a profound deficiency in CD4+ T cells but normal numbers of CD8+ T cells ?

What is the name of this syndrome ?

A

Absent expression of MHC class II molecules. (Means that T cells cant undergo affinity selection in the thymus to become CD4+)

Bare Lymphocyte syndrome -Type 2 (BLS type 2)

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9
Q

Why do you get a reduction/absence in IgG and IgA immunoglobulins with CD4+ T cell defficiency (e.g in BLS type2) ?

A

The CD4+ T helper cells are involved in B cell Isotope switching so you have IgM B cells but cant switch to IgG/ IgA in the germinal centres.

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10
Q

What is the definitive treatment of SCID and BLS type 2 ?

A

Haematopoeitic stem cell transplant

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11
Q

How do you treat ADA SCID ?

A

Enzyme replacement therapy

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12
Q

Which bacterial infection are patients with an IFN gamma deficiency particularly susceptible to ?

A

Recurrent Mycobacterium Marinum infections (atypical mycobacterium)

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13
Q

22q 11.2 deletion syndrome is also known as ???

A

DiGeorge syndrome

Defect in the development of the pharyngeal pouch

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14
Q

Is the IgM B cell response T cell dependent ?

A

No

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15
Q

How do CD4+ T cells help B cells undergo B cell differentiation ?

A

CD40 ligand is expressed on CD4+ Th cells and this acts on CD40 receptors on B cells causing isotope switching.

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16
Q

Which part of an Antibody identifies pathogens/toxins ?

A

Fab region

17
Q

Which part of an antibody interacts with Complement/phagocytes/NK cells ?

A

Fc region

18
Q

Which X-linked disease stops B cells leaving the bone marrow and hence is associated with a deficiency in mature B cells and antibodies ?

A

Bruton’s X linked agammaglobulinaemia

19
Q

Which X-linked syndrome is associated with failure of B cell maturation and isotype switching causing an elevated serum IgM but no IgG/IgA?

A

Hyper IgM syndrome

Mutation in CD40 ligand on T cells which means CD4+ T helper cells cant help B cells to undergo Maturation in germinal centres

20
Q

Which immune deficiency disease is associated with poor response to immunisation, with low IgG/ IgA / IgM ?

A

Common variable immune deficiency

Not much known but it is a defect in production of Immunoglobulins
They get a lot of inflammatory and auto-immune diseases

21
Q

Which immunodeficiency disease is associated with recurrent respiratory tract infections, low IgA levels and normal levels of all other immunoglobulins ?

A

IgA deficiency

22
Q

Which genetic mutation is associated with Wiskott-Aldrich syndrome ?

A

WASp gene

23
Q

Which mutation is associated with Bare lymphocyte syndrome type 2 ?

A

MHC class II

24
Q

Which mutation is associated with SCID ?

A

IL-2 receptor

25
Q

Which mutation is associated with Bruton’s X-Linked Agammaglobulinaemia ?

A

BTK gene

26
Q

Which lymphocytes respond to foreign HLA-DR types ?

A

CD4 + T cells

27
Q

Which lymphocytes respond to foreign HLA-B types ?

A

CD8+ T cells

28
Q

Patient presents with recurrent nose bleeds, easy bruising and blood in the stool. Blood tests reveal a thrombocytopenia, elevated IgA and IgE and reduced IgM levels.

Most likely diagnosis ?

A

Wiskott-Aldrich syndrome

29
Q

Patient presents with jaundice and hepatomegaly. His bloods show a low CD4+ T cell level but normal CD8+ level.

Most likely Diagnosis?

A

Bare lymphocyte syndrome Type 2

30
Q

Young girl presents with recurrent skin infections with a normal neutrophil count and a NTB test remains colourless

Most likely diagnosis ?

A

Chronic granulomatous disease.

Caused by a deficiency in NADPH which causes absence of the respiratory burst.