16- Paediatric immunology

Question 1

innate immune system

Answer 1

• Non-specific
• Rapid
• Key protection
  o Macrophages
  o Neutrophils
  o Complement

Question 2

Adaptive

Answer 2

• Specific
• Slower onset
• Pathogen specific
• Key protection
  o T cells
  o B cells/ plasma cells

Question 3

types of antibodies

Answer 3

IgG, IgA, IgM, IgE, IgD

Question 4

IgG

Answer 4

– main one in the blood, multiple subtypes, memory response

Question 5

IgA

Answer 5

in the mucosa, most abundant overall

Question 6

IgM

Answer 6

early response, binds complement, limited memory response

Question 7

IgE

Answer 7

mast cell activation, allergy and parasitic response

Question 8

types of primary immunodeficiency disorders

Answer 8

• Antibody (B cell)
• Combined (+T cells)
• Complement
• Phagocyte (chronic granulomatous disease

Question 9

types of immunodeficiency related to Antibodies

Answer 9

o X linked agammaglobulinaemia (XLA)
o Specific Antibody deficiency
o Transient hypogammaglobulinaemia of Infancy
o IgG subclass deficiency/IgA deficiency

Question 10

history taking for immunodeficiency

Answer 10

Infection history
o Site
o Frequency
o Need for admission/ IV antibiotics

Immunisation status

Family history
o Infections
o Autoimmunity
o Consanguinity
o Neonatal deaths

Question 11

presentation of primary immunodeficiency disorders

Answer 11

• Serious e.g. recurrent deep abscess
• Persistent e.g. long course of antibiotics, thrush
• Unusual
• Recurrent e.g. >4 ear infection, >2 sinusitis, >2 pneumonia

Question 12

investigations for PID (primary immunodeficiency)

Answer 12

• FBC
• Lymphocyte subsets
• Total antibodies
• Specific antibodies
  o Vaccination history
• Neutrophil oxidative burst
• Complement (CH50/AP50)
• HIV

Question 13

antibody deficiency syndrome types

Answer 13

o X linked agammaglobulinaemia (XLA)
o Specific Antibody deficiency
o Transient hypogammaglobulinaemia of Infancy
o IgG subclass deficiency/IgA deficiency

Question 14

cause of antibody deficiency syndrome

Answer 14

mutation in genes which code for correct production of antibodies

Question 15

presentation of antibody deficiency syndrome

Answer 15

• Starts at 6-12 months after maternal antibodies have waned
• Bacterial infection
• Sino-pulmonary infection
  o Tricky as these are common
  o Hospital admission, CXR changes
  o Recurrent otitis media with discharge
• Giardia

Question 16

management of antibody deficiency syndrome

Answer 16

• Immunoglobulin replacement – IgG subcut (or IV)
• Prompt, prolonged courses of antibiotics
• Antibiotic prophylaxis

Question 17

complement disorders background

Answer 17

Functions of complement
- Opsonisation flags cells for phagocytosis
- Chemo-attraction to recruit more phagocytes
- Membrane attack complex creates holes in certain types of bacteria (encapsulated)

Question 18

complement disorders background

Answer 18

Functions of complement
- Opsonisation flags cells for phagocytosis
- Chemo-attraction to recruit more phagocytes
- Membrane attack complex creates holes in certain types of bacteria (encapsulated)

Question 19

presentation of complement disorders

Answer 19

• Recurrent invasive bacterial disease
  o Meningitis, pneumonia
• Meningococcal, Pneumococcal, Hib
• Usual, but frequent, sinopulmonary infection organisms in early pathway defects

Question 20

managment of complement disorders

Answer 20

• Penicillin prophylaxis
• Additional immunisations
  o Men ACWY, Men B, Pneumovax
• Check ‘green book’
• Immunisation against Infectious Disease

Question 21

phagocyte disorders background

Answer 21

Role of phagocytes
- Neutrophils
- Phagocytosis
- This is primarily bacteria, but remember fungi as well
- Act as Antigen Presenting Cells, so a loss of neutrophil function is a problem
- Most of these have normal neutrophil numbers and there are few functional tests

Question 22

types of phagocyte disorders

Answer 22

• Chronic Granulomatous Disease
  o X linked
  o Or Autosomal recessive
• Severe Congenital neutropenia
• Leucocyte Adhesion Defects

Question 23

presentation of phagocyte disorders

Answer 23

• Recurrent abscesses – Staph aureus
• Fungal chest infections
• Liver abscess
• Osteomyelitis
• BCG -it is
• Early onset Inflammatory Bowel Disease

Question 24

management of phagocyte disorders

Answer 24

• Anti fungal and antibiotic prophylaxis
• Avoid fungal spores eg compost, leaf mulch.
• Avoid BCG.
• Consider Bone Marrow Transplant, esp with early diagnosis

Question 25

Combined immune deficiencies background

Answer 25

• T cell defects +/- others
• Due to complex T cell interaction with B cells, impacts antibody response also.

Question 26

types of combined immune deficiencies

Answer 26

• Severe combined immunodeficiency (SCID)
  o Many categories e.g. all are T- but can also be B+ or B-
• Hyper IgM syndrome
• Complete Di George (missing thymus)

Question 27

role of T cells

Answer 27

• CD4 T cells – helper cells, activate macrophages and B cells
• CD8 T cells – anti-viral, induce apoptosis, anti tumour
• Tregs – immunoregulatory, loss leads to autoimmunity

Question 28

investigation for combined deficiency

Answer 28

• Lymphocytes <2.8x10^9 <1 year

Question 29

presentation for combined deficiency

Answer 29

• EVERY infection
• Recurrent bacterial infections
• Viral- systemic, persistent
• Mycobacteria
• Candida
• Aspergillus
• Cryptosporidium
• PJP
• Chronic diarrhoea and faltering growth

Question 30

management of SCID

Answer 30

• Bone marrow transplant is aim, before significant morbidity- curative
• Prophylactic antibiotics and antifungals
• Immunoglobulin replacement
• Infection prevention measures
• CMV neg, irradiated blood products
• Avoid live vaccines

Question 31

syndromes related to immune deficiencies

Answer 31

• Di George (no thymus)
• Ataxia telangiectasia
• CHHARGE syndrome

Question 32

Many syndromes may have other features that predispose to frequent infections

Answer 32

e.g.
- Poor tone leading to weak cough
- Indwelling devices
- Reflux