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Year 5 path SW COPY > Immuno 4: Primary Immune Deficiencies 2 > Flashcards

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 and production of immature B 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/ absent 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

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17
Q

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

A

Fc region

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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

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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

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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

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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

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22
Q

Which genetic mutation is associated with Wiskott-Aldrich syndrome ?

A

WASp gene

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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.

31
Q

when is the thymus most active

A

fetal and neonatal period

32
Q

what is the most severe form of SCID and what is the mutation

A

reticular dysgenesis

mutation in mitochondrial energy metabolism enzyme adenylate kinase 2 (AK2)

33
Q

phenotype of X linked SCID

A

very low/ absent T cell numbers
normal/ increased B cell numbers
very low/ absent NK cell numbers

34
Q

what is the clinical phenotype of SCID

A 
unwell by 3 months 
infections of all types 
failure to thrive 
persistent diarrhoea 
unusual skin disease 
family history of early death
35
Q

what is the function of CD8+ T cells

A

cytotoxic cells
recognise peptides derived from IC proteins in association with HLA class I
HLA - A, B, C
kills cells directly - perforin, granzymes, expression of Fas ligand (causes)
important in the defence against viral infections and tumours

36
Q

what is the function of CD4+ T helper cells

A

recognise peptides derived from EC proteins
presented on HLA class II
HLA - DR, DP, DQ
immunoregulatory functions via cell: cell interactions and expression of cytokines (provide help for a full B cell response, and some CD8+ T cell responses)

37
Q

features of di George syndrome

A

22q11.2 deletion
thymus not fully developed
developmental defect of the pharyngeal pouch
high forehead, low ears, cleft palate, small mouth and jaw
underdeveloped parathyroid, oesophageal atresia, underdeveloped thymus, complex congenital heart disease
normal B cell numbers, low T cell numbers, immune function mildly improves with age

38
Q

features of bare lymphocyte syndrome (BLS) type 2

A 
defect in regulatory protein involved in expression of class II genes 
- regulatory factor X 
- class II transactivator
leads to absent MHC class II 
deficiency of CD4+ cells

normal CD8+
normal B cell
low IgG or IgA

39
Q

clinical features of BLS type 2

A

unwell by 3 months
infections of all types
failure to thrive
family history of early infant death

40
Q

how can we investigate T cell deficiencies

A 
total WCC and differential (higher in children)
lymphocyte subsets - CD4, 8, B, NK 
immunoglobulins 
functional tests 
HIV test
41
Q

how can we manage immunodeficiencies to do with T cells

A

aggressive prophylaxis/ treatment of infection
haematopoietic stem cell transplantation
enzyme replacement therapy - PEG-ADA, ADA SCID
gene therapy
thymic transplantation - to promote T development in di george syndrome

42
Q

what is the classic presentation of X linked SCID

A 
severe recurrent infections from 3 months 
CD4 and CD8 cells absent 
B cells present 
Ig low 
normal face and ECG
43
Q

what is the classical presentation of IFN g receptor deficiency

A

young adult with chronic infection with mycobacterium marinum

44
Q

what is the classical presentation of 22q 11.2 deletion syndrome

A

recurrent infections in childhood, abnormal facial features, CHD, normal B cells, low T cells, low IgA, low IgG

45
Q

what is the classical presentation of BLS type II

A

6 month baby with 2 recent serious bacterial infections
T cells present but only CD8+
B cells present
IgM present, IgG low

46
Q

what is brutons X linked hypogammaglobulinaemia

A

B cells do not mature
no antibodies produced
caused by an abnormal B cell TK gene (BTK)
absence of mature B cells

47
Q

what are the clinical features of brutons X linked hypogammaglobulinaemia

A

boys present in first few years
recurrent bacterial infections
viral, fungal, parasitic
failure to thrive

48
Q

features of hyper IgM syndrome

A

mutation in CD40 ligand gene (CD40L, CD154)
CD4+ cells cannot signal to B cells
blocks the maturation of IgM B cells through germinal centres

normal number of circulating B cells 
normal number of T cells 
no germinal centre development within LN and spleen 
failure of isotope switching 
elevated serum IgM 
undetectable serium IgG, A, E
49
Q

clinical phenoype of hyper IgM

A

boys present in first few years
reuccent bacterial infections
Pneumocystsis jirovecii
failure to thrive

50
Q

features of common variable immunodeficiency

A 
reduction in IgG, low IgA or IgM 
poor/absent response to immunisation 
recurrent bacterial infections 
pulmonary disease 
GI disease 
AI disease 
malignancy - NHL
51
Q

features of selective IgA deficiency

A

common
many asymptomatic
1/3 have recurrent RTIs

52
Q

how can we investigate B cell deficiencies

A 
total WCC 
lymphocyte subsets 
serum Ig and protein electrophoresis 
functional tests of B cell function 
protein electrophoresis - gamma peak = all the antibodies 
antibody deficient = no gamma peak
53
Q

how can we manage immunodeficiency cause by B cells

A

aggressive prophylaxis/ treatment
Ig replacement
immunisation not worthwhile unless for selective IgA deficiency

54
Q

what is the classical presentation of common variable immunodeficiency

A

bronchiectasis, recurrent sinusitis, development of atypical SLE

55
Q

what is the classical presentation of X linked hyper IgM syndrome due to CD40L mutation

A

bacterial infections as a child, episode of PCP, high IgM, absent IgA, absent IgG

56
Q

what is the classical presentation of IgA deficiency

A

recurrent RTI
absent IgA
normal IgM
normal IgG

Year 5 path SW COPY (106 decks)

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