Allergy And Immunology

Question 1

In which primary immunodeficiency is there a failure to generate mature B-cells?

Answer 1

X-linked agammglobulinaemia (Brutons disease). Failure of b-cells leads to inability to produce immunoglobulins (part of the humoral antibody response). Hx of recurrent bacterial infections. Rx IV Ig

Question 2

Which primary immunodeficiency is thought to be the most severe and why?

Answer 2

Severe combined immunodeficiency (SCID) effects both the humoral (b-cell) and the cell mediated (t-cell). Famous ‘bubble baby disease’. Dx: lymphopenia. Rx: BM transplant can be curative.

Question 3

Which primary immune deficiency is characterised by the failure of phagocytic cells to kill organisms?

Answer 3

Chronic granulomatous disease (CGD). Lack of superoxide radicals produced by the phagocytes (e.g. neutrophils, monocytes and macrophages using NADPH oxidase), leads to failure to kill organisms and the creation of granulomas and abscesses at these sites.

Question 4

Which immune deficiency disorder has low levels of serum IgG and IgA?

Answer 4

Common variable immunodeficiency (CVID). Criteria: IgG and IgA <2 standard deviations below the mean, Impaired vaccine response and exclusion of other causes of hypogammaglobulinaemia.

Question 5

What are the different types of hypersensitivity?

Answer 5

Type 1: allergy (immediate) - IgE - mast cells and basophils
Type 2: antibody dependant/cytotoxic - IgG or IgM
Type 3: immune complex disease - IgG - serum sickness - soluble antigen
Type 4: delayed-type hypersensitivity/ cell mediated/Antibody-independent - T-cells - chronic
Type 5: autoimmune disease - igG or IgM e.g. Graves’ disease or myasthenia graves

Question 6

Which order do the atopic diseases normally develop in children?

Answer 6

Eczema
Food allergy
Rhinitis (hay fever)
Asthma

Question 7

90% of anaphylaxis in children is due to food. Which are the most common food allergens?

Answer 7

Milk, egg, peanuts, tree nuts, fish, soya, wheat, shellfish, sesame, kiwi

Question 8

When testing for food allergy what is the gold standard test?

Answer 8

Food challenge (comes after skin prick test). Can only be done in hospital due to anaphylaxis risk.

Question 9

Which common infantile allergy do children normally grow out of?

Answer 9

85% of children grow out of cows Milk protein allergy by 3 years. (Peanut allergy is often lifelong)

Question 10

How would you manage acute anaphylaxis in children?

Answer 10

ABC
Removed allegen (if possible)
IM adrenaline (epinephrine)
IV hydrocortisone and antihistamine (chlorphenamine)

Question 11

What are the signs associated with anaphylaxis?

Answer 11

Mucosal involvement (hives, pruritis, swelling tongue/lips) with:

Resp: dyspnoea, wheeze, strider, hypoxia
Cardio: hypotension, tachycardia, syncope
GI: crampy abdominal pain, diarrhoea, vomiting

Question 12

Can children with egg allergy have vaccines? E.g. MMR and influenza

Answer 12

MMR- yes- grown in chick fibroblasts

Influenza and yellow fever - no

Question 13

What is hyper IgE syndrome?

Answer 13

Resp infections
Eczimatiod eruptions
Cold abscesses ( non painful masses)
Mucocutsneous candidiasis

Coarse facial features
Two sets of teeth (peculiarity)