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Paediatrics RACP Exam Study > Paediatric Immunology 1 > Flashcards

Paediatric Immunology 1 Flashcards

1
Q

What immunodeficiency is invasive Neisseria infection associated with?

A
  • Membrane attack complex deficiency (C5-9, typically presents with recurrent meningicoccal meningitis after age 10, also susceptible to disseminated gonococcal infections)
  • Properidin deficiency (poor prognosis)
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2
Q

What immunodeficiencies is MSMD associated with?

A
  • IFN-gamma receptor 1+2, IL12B, IL12RB1, IKBKG

- STAT1 most serious, also get viral

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3
Q

What immunological issues are associated with eczema?

A
  • Wiskott-Aldrich syndrome
  • IPEX
  • hyper-IgE syndromes
  • hypereosinophilia syndromes
  • IgA deficiency
  • CVID
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4
Q

What immunological issues are associated with oral/nail candidiasis?

A
  • T-cell problems
  • CID/SCID
  • mucocutaneous candidiasis
  • hyper-IgE syndromes
  • MSMD
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5
Q

What infections are neonates particularly susceptible to and why?

A
  • Gram negative organisms

- IgM does not cross the placenta

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6
Q

Describe the presentation and findings in X-linked agammaglobulinaemia:

A
  • Bruton tyrosine kinase deficiency
  • Presents 6-8 months when maternal Ig levels fall, pneumococcal/Hib sinopulmonary infections
  • No B cells
  • ALL Ig low/absent unless maternal IgG
  • Lymphoid hypoplasia (no LN, tonsils, thymus)
  • Poor vaccine response
  • susceptible to extracellular bacteria and viruses
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7
Q

What drugs are associated with CVID/IgA deficiency?

A
  • Phenytoin
  • d -penicillamine
  • gold
  • sulfasalazine
  • Carbamazepine
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8
Q

Describe the presentation and findings in X-linked hyper-IgM syndrome:

A
  • Class-switch recombination defects=B cells prefer IgM production
  • Normal/high IgM and low/absent IgG/A/E

Type 1 X-linked - CD40 ligand Xq26 or NEMO

  • sinopulmonary, OM, tonsillitis, PJP
  • crypto, verruca, liver disease, malignancy
  • NEMO - anhydrotic ectodermal dysplasia
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9
Q

Describe the presentation and findings in X-linked lymphoproliferative/Duncan disease:

A
  • Deficient adhesion molecule on thymocytes, T-cells, NK cells - leads to antibody deficiency + uncontrolled cytotoxic T-cell response to EBV.
  • Gene SH2D1A
  • Well until EBV (<5yo)
  • 50% fulminant/fatal EBV
  • 25% (B cell) lymphoma
  • 25% acquired hypogammaglobulinaemia/CVID
  • 70% dead at 10yo
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10
Q

Which B-cell defects are treated with BMT/stem cell transplant?

A
  • X linked lymphoproliferative disease

- X linked hyper IgM

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11
Q

What screening test can be done for SCID?

A
  • Heel prick T cell lymphopenia

- T-cell receptor recombination excision circles are absent or extremely low - PCR

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12
Q

What other pathogens might you be susceptible to if you have MSMD?

A

Interferon gamma receptor 1/2 - listeria, salmonella and regular Tb

Interleukin 12 - salmonella (typhi and non-typhi)

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13
Q

What x-ray findings do you expect with ADA-SCID?

A
  • No thymus, pneumonia
  • Ribs - rachitic rosary (widened costo-chondral junction ant. ribs, also seen in rickets)
  • Other areas chondroosseous dysplasia (iliac apophyses, vertebral bodies)
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14
Q

What cytokines do TH-1 cells secrete?

A
  • IFN-gamma (also IL-2 and tumor necrosis factor-beta)
  • cell-mediated immunity (macrophage, IgG)
  • phagocyte-dependent inflammation
  • kill intracellular organisms e.g. viral
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15
Q

What cytokines do TH-2 cells secrete?

A
  • IL-4, IL-5, and IL-13
  • strong antibody responses (including IgE)
  • eosinophil accumulation IL-5
  • inhibit several functions of phagocytic cells (phagocyte-independent inflammation)
  • fight helminthic parasites
  • (also IL-6, IL-9, IL-10 but less important)
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16
Q

What do dendritic cells do?

A
  • APC
  • CD28:B7 interaction
  • activate naive T cells -> clonal expansion and differentiation into effector T cells
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17
Q

What are the markers of NK cells? What do NK cells do?

A
  • CD16 and CD56
  • Kill virally infected cells
  • Kill some types of tumour cells
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18
Q

What are the clinical features of cartilage hair hypoplasia?

A
  • Amish, RMRP 9p21-p13
  • short, pudgy hands; redundant skin
  • hyperextensible hands and feet but can’t extend elbows completely
  • fine, sparse, light hair and eyebrows- CID (most common) or SCID
  • varicella, vaccine disease, vaccinia
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19
Q

What are the clinical features of MHC Class II deficiency?

A
  • HLA-DR, -DQ, and -DP deficiency
  • North African descent
  • Diarrhoea early infancy with cryptosporidiosis and enteroviral infections (e.g., poliovirus, coxsackievirus)
  • herpesviruses, oral candidiasis, bacterial pneumonia, PJP, septicemia
  • NO disseminated infection from BCG/GVHD from transfusion.
  • normal B cells, low CD4, normal-increased CD8
  • no antigen response (usually MHC II on APCs)
  • hypogammaglobulinemia
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20
Q

Immunodeficiency with Thrombocytopenia and Eczema is also known as:

A

Wiskott-Aldrich Syndrome

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21
Q

How do you test for CGD?

A

Chronic granulomatous disease (CGD) related to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase enzyme complex problems

The nitroblue-tetrazolium test is the original and most widely-known test for chronic granulomatous disease. It is negative in CGD.

You can also do the DHR test now which is what we use.

22
Q

Which cells produce IL-1 and 2?

A

Macrophages and polymorphs and have a target effect on T/B/NK cells

23
Q

How might Wiskott-Aldrich syndrome present?

A
  • Male with: eczema, thrombocytopenia (low platelet count), immune deficiency
  • prolonged bleeding if circumcised
  • bloody diarrhoea
  • infections (meningitis, sepsis, pneumonia, OM)
  • strep. pneumoniae
  • later in life: PJP, EBV malignancy
24
Q

What lab findings might there be in Wiskott-Aldrich syndrome?

A
  • Thrombocytopenia
  • Low/absent isohemagglutinins
  • Poor response to polysaccharide immunisation (Prevenar)
  • Low IgM, High IgA/IgE, normal IgG
  • Low T cells
25
Q

What infections are you susceptible to if you have a mutation of your NK cells?

A
  • HPV

- treat with antiviral prophylaxis and stem cell transplant

26
Q

What mutations are implicated in hyper-IgE syndrome?

A
  • STAT3 is Buckley Syndrome/AD form

- DOCK8 or TY2 is AR form

27
Q

What is the most common immunodeficiency?

A
  • Selective IgA deficiency

- US stats - 0.33% or 1/500

28
Q

How do we give immunoglobulin replacement therapy and why?

A
  • humoral immune defects
  • IVIG (Intragram P) q3-4 weekly or SCIG (Evogam) weekly
  • Dose: ~300-600mg/kg/month
  • Aim for IgG trough or steady state 7-8g/L
29
Q

What drugs are associated with hypogammaglobulinaemia?

A
  • Antimalarials
  • Captopril
  • Glucocorticoids
  • Carbamazepine
  • Phenytoin
  • Sulfasalazine
30
Q

What genetic disorders are associated with hypogammaglobulinaemia?

A
  • SCID
  • Hyper IgM
  • Ataxia-telangiectasia
  • Monosomy 22
  • Trisomy 8, 21
31
Q

What infections are associated with hypogammaglobulinaemia?

A
  • Congenital toxo, CMV, rubella
  • HIV
  • EBV
32
Q

Which vaccinations are T-cell dependent VS T-cell independent?

A
  • T-dependent are protein vaccinations (Tetanus, Diptheria, HiB, Prevenar)
  • T-independent are polysaccharide vaccinations (Pneumovax23)
33
Q

What is the abnormality in Wiskott-Aldrich Syndrome?

A
  • X-linked, defective WASP gene
  • defective anti-polysaccharide antibody, impaired T cell activation
  • Susceptible to encapsulated extracellular bacteria
34
Q

How might autoimmune lymphoproliferative syndrome present?

A
  • 1st year of life (definitely symptoms by age 5)
  • autoimmune problems
  • CNS issues (seizure, headache, encephalopathy)
  • lymphadenopathy
  • splenomegaly, hepatomegaly (50%)
  • malignancies

Lab findings - hypergammaglobulinemia (IgG, IgA), cytopenias due to big spleen, autoimmune anaemia/thrombocytopenia/neutropenia

35
Q

What does IPEX stand for?

A
  • Immune dysregulation
  • Polyendocrinopathy
  • Enteropathy
  • X linked
36
Q

Describe the presentation of IPEX:

A
  • Male (X-linked)
  • Erythroderma (infants) + Eczema
  • Enteropathy with neonatal watery diarrhoea, FTT
  • Polyendocrinopathy
  • Immune dyresgulation with serious bacterial infections, allergies, autoimmune, lymphadenopathy and splenomegaly
37
Q

Describe the presentation of SCID:

A
  • Unwell < 3/12
  • Persistent diarrhoea, FTT
  • Infections - severe common infections, PJP, vaccine associated
  • Viral eg. CMV/adeno
  • Fungal – persistent thrush
38
Q

What cytokines do TH17 cells secrete?

A
  • IL-17 A and F, IL-22
  • Neutrophil/monocyte activation
  • extracellular bacteria and fungi
39
Q

What role do different TH cells play in cell damage?

A
  • TH-1 autoimmune disease, tissue damage with chronic infection
  • TH-2 allergic
  • TH-17 organ specific
40
Q

What different phenotypes are there for SCID and what are the genetic associations?

A
  • T- B+ NK+ IL7 receptor alpha deficiency
  • T- B+ NK- X linked/common gamma chain SCID 45% or JAK 3
  • T- B- NK+ ADA SCID or RAG 1/2
  • T- B- NK- Adenosine deaminase deficiency SCID
41
Q

What specific immunodeficiencies might you consider in Staphylococcus epidermidis infection?

A
  • Neutropenia

- Leukocyte adhesion defects

42
Q

What specific underlying issues might you consider in burkholderia cepacia infection?

A
  • Chronic Granulomatous Disease
  • Cystic Fibrosis
  • Sickle-cell haemoglobinopathies
43
Q

What is the aetiology of Chédiak-Higashi syndrome?

A
  • Autosomal recessive degranulation problem
  • Disordered coalescence of lysosomal granules
  • Large granules in multiple tissues
  • Responsible gene is CHSI/LYST (regulates granule fusion)
44
Q

What are the half-lives of different immunoglobulin subtypes?

A 
Ig A - 6 days
Ig D - 3 days
Ig E - 2 days
Ig G - 3 weeks (7-23 days depending on subclass)
Ig M - 5 days
45
Q

What % of normal infants have delayed separation of the cord (3/52 or later) ?

A

10% of healthy infants can have cord separation at age 3 wk or later

46
Q

How do leukocyte adhesion deficiencies present?

A
  • Infancy, delayed separation of cord with omphalitis
  • recurrent infections skin, mouth, resp, lower GI, genital mucosa
  • neutrophilia
  • skin infections - large chronic ulcers, minimal inflammation
  • gingivitis + tooth loss
47
Q

How does Chediak-Higashi Syndrome present?

A
  • increased susceptibility to infection
  • mild bleeding
  • partial oculocutaneous albinism
  • progressive peripheral neuropathy
  • haemophagocytic lymphohistiocytosis (HLH) in 85%
48
Q

How does AD Hyper-IgE syndrome present?

A
  • AD form - STAT3 or Buckley Syndrome
  • Recurrent severe skin and sinopulmonary infections
  • staph. aureus, s. pneumoniae, h. influenzae
  • eczema
  • mucocutaneous candidiasis
  • retained primary teeth
  • minimal trauma fractures/scoliosis
  • characteristic coarse facies
49
Q

How does AR Hyper-IgE syndrome present?

A
  • DOCK8 gene
  • atopy
  • increased viral susceptibility and sepsis
  • no MSK/dental, more malignancy
  • Recurrent pneumonia without pneumatoceles
  • boils, mucocutaneous candidiasis
  • neurologic symptoms
50
Q

Describe the findings in Type 2 hyper IgM syndrome:

A

Type 2, AICDA Chromosome 12

  • Normal/high IgM and low/absent IgG/A/E
  • lymphoid hyperplasia, no PJP
  • tendency to autoimmune/inflammatory problems
  • RX IVIG, early abs
51
Q

Describe the findings in Type 3 hyper IgM syndrome

A
  • Type 3, CD40 chromosome 20
  • Normal/high IgM and low/absent IgG/A/E
  • sinopulmonary, OM, tonsillitis, PJP
  • crypto, verruca, liver disease, malignancy
  • RX IVIG, GCSF, stem cell transplant

Paediatrics RACP Exam Study (30 decks)

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