Session 2: A Clinical Approach to Allergy

Question 1

What is an allergen?

Answer 1

Any substance stimulating the production of IgE or a cellular immune response.

Allergens are usually proteins but not always. They can also be carbs.

Question 2

Define sensitivity.

Answer 2

Normal response to stimulus

Question 3

Define hypersensitivity

Answer 3

Abnormal strong response to a stimulus

Question 4

What is sensitisation?

Answer 4

Production of IgE antibodies after repeated exposure to an allergen.

Question 5

What is allergy?

Answer 5

A hypersensitivity reaction initiated by a specific immunological mechanism, that is IgE-mediated (such as peanut) or non-IgE mediated (such as milk allergy).

Question 6

What is atopy?

Answer 6

A personal or familial tendency to produce IgE in response to exposure to potential allergens.

Question 7

What is anaphylaxis?

Answer 7

A serious allergic reaction with bronchial, laryngeal and cardiovascular involvement that is rapid in onset and can cause death.

Question 8

What is food allergy?

Answer 8

A immunologically medaited adverse reaction to foods.

Question 9

Presentation of allergic rhinitis or hay fever.

Answer 9

Persisten or recurrent block or runny nose.

Itch and sneezing.

Question 10

Common symptom triggers of allergic rhinitis.

Answer 10

Grass and tree pollens

House dust mites.

Question 11

Presentation of allergic conjunctivitis.

Answer 11

Red, swollen, watery and itchy eyes.

Itch is a key symptom to distinguish this form of conjunctivitis from others.

Question 12

Presentation of allergic asthma.

Answer 12

Wheeze

Cough

Shortness of breath

Tight chest

Question 13

Presentation of atopic dermatitis/eczema.

Answer 13

Itchy skin with scratching leading to chronic skin changes.

Question 14

Classifications of urticaria/hives.

Answer 14

Less than 6 weeks = acute

More than 6 weeks = chronic

Question 15

Most allergen of insect allergy in the UK.

Also give presentation.

Answer 15

Stings from wasps or bees.

Presentation can be mild with a large localised sting reaction characterised by redness, swelling and itch.

Question 16

Define food allergy.

Answer 16

An adverse health effect arising from a specific immune response that occurs on exposure to a food. The definition encompasses responses that are classified as IgE or non IgE mediated.

Question 17

Difference between food allergy and food intolerance.

Answer 17

Food intolerance is an adverse response that does not involve an immune response.

Question 18

Most common food allergies

Answer 18

Milk

Egg

Peanuts

Question 19

Give examples of food characteristics in food intolerances.

Answer 19

Reactions to pharmacologically active food components or illness in resposne to toxins from microbial contamination or to scromboid fish toxin.

E.g. from eating spoiled fish.

Question 20

How does host characteristics food intolerance differ to food characteristics?

Answer 20

Host characteristics include metabolic disorders such as lactose intolerance and psychological or neurological responses such as food aversion or rhinorrhoea caused by spicy foods.

Question 21

Answer 21

Question 22

IgE mediated food allergic symptoms of the skin.

Answer 22

Pruritus

Erythema

Urticaria

Angioedema of lips, face and eyes

Question 23

IgE mediated food allergic symptoms of GI.

Answer 23

Angioedema of lips, tongue and palate

Oral pruritus

Colicky abdominal pain

Nausea

Vomiting

Diarrhoea

Question 24

IgE mediated food allergic symptoms of resp system.

Answer 24

Runny and/or blocked nose

Sneezing

Itchy nose

Croupy cough

Stridor

Breathlessness

Cough

Wheeze

Question 25

IgE mediated food allergic symptoms of CVS.

Answer 25

Pallor

Drowsy

Hypotension

Question 26

How does non-IgE mediated symptoms differ?

Answer 26

Usually vague with abdo pain and not clearly associated with food contact due to the delayed presentation.

Can mimic other common GI conditions.

Question 27

Specific disorders of IgE mediated allergy.

Answer 27

Urticaria/Angioedema

Anaphylaxis

Food-associated exercise induced anaphylaxis

Polled food syndrome

Question 28

Common food triggers leading to anaphylaxis.

Answer 28

Nuts

Fish

Shellfish

Milk

Egg

Question 29

What is food-associated exercise induced anaphylaxis?

Answer 29

Food triggers anaphylaxis only if ingestion is followed temporally by exercise.

Question 30

Specific disorders of non-IgE mediated food allergy.

Answer 30

Proctocolitis

Enterocolitis

Eosinophilic oesophagitis

Food protein induced enterocolitis syndrome (FPIES)

Question 31

What is the most common food allergy in adults?

Answer 31

Pollen food syndrome

Question 32

What does heat-stable or heat-labile allergens mean?

Answer 32

Heat-stable allergens will persist if food is cooked/heated.

Heat-labile will not.

This means if you cook a heat-labile food that you are usually allergic to, you won’t be after it is cooked.

Question 33

Give an example of a matrix effect on a food allergen.

Answer 33

Baked milk that is found in processed biscuits has a lower allergenicity and availability to the immune system.

This means it can be used in order to reintroduce milk back in to the diet.

Question 34

What is cross-reactive food allergens?

Answer 34

Foods are related and this means that if you are allergic to one food, you might be allergic to a similar food as well.

An example is if you are allergic to one nut there is a risk you are allergic to more nuts.

Question 35

Food allergy screening tests.

Answer 35

Skin prick tests (STPs) of assay of serum specific IgE.

Can be used to test foods for which there are no blood tests available.

Prick-prick tests (prick food first and then prick skin)

Can test for IgE antibodies but that only determines the presence of sensitivity and not allergy.

Question 36

How to treat food allergies.

Answer 36

If they do not resolve it is usually done by desensitisation to the allergen.

An example of this is to give the patient some crumbles of a biscuit with baked milk. And then gradually step it up until milk is reintroduced and does not give an allergic response.