Semester 4

Question 1

What effect does processing have on the allergenic properties of milk?

Answer 1

Casein is much more heat stable than whey. When baked with wheat the milk proteins form bonds in the food matrix so they are much less liable to cause reactions. Up to 70% of kids with a milk allergy can tolerate milky biscuits.

Question 2

What effect does processing have on the allergenic properties of eggs?

Answer 2

There are four major egg white proteins, all of which except for ovomucoid are heat labile. Well cooked/baked eggs are much less allergenic than raw egg.

Question 3

What effect does processing have on the allergenic properties of peanuts?

Answer 3

Dry roasting (common in the west) increases allergenicity, this decreases if they are boiled or fried.

Question 4

What effect does processing have on the allergenic properties of fish?

Answer 4

Fish proteins are very heat stable. Only tinned tuna/salmon have lower risk levels.

Question 5

What effect does processing have on the allergenic properties of apple?

Answer 5

Apple proteins are very heat labile so people suffering from pollen food syndrome are fine with cooked fruit products. Pasteurised juices also?

Question 6

What is the difference between a ‘conformational’ or ‘sequential’ epitope and how does heat disrupt each?

Answer 6

Conformational contains residues from different parts of the primary structure close together in the tertiary structure. These are prone to disruption when the food is heated. A sequential epitope is formed from a series of AA’s that exist in their sequence in the primary structure and thus are very heat stable. Casein is a good example of this and heating this food will not make it less allergenic.

Question 7

Name some important cross reactions within the following groups:

• Milks
• Nuts
• Fish-
• Shellfish
• Tree/grass pollens.

Answer 7

• Milk - if you are allergic to cow’s milk there is a 92% chance you will be allergic to the milk of other animals such as goats. Avoid animal milk.
• Nuts: Peanuts (legumes) and tree nuts are different so the cross reactivity exists (rate 37%) between different types of tree nuts.
• Fish: If you are allergic to one fish you have a 50:50 chance of being allergic to another.
• Shellfish: 75% chance of being allergic to another.
• Pollens: Over half of people allergic to tree/grass pollens are allergic to fruit/veg pollen.

Question 8

Explain the process for performing an allergen specific IgE immunoassay.

Answer 8

1: Take a tube with the allergen of interest attached to the bottom.
2: Wash test reagent with the patient’s serum.
3: Wash with clean water.
4: Use a labelled anti-human IgE.
5: Wash again and then use correct method to detect presence of the anti-human IgE.

Question 9

How do IgE levels and skin prick tests correlate with clinical allergy?

Answer 9

Merely having a reaction does not confer a clinical allergy, nor does it predict severity. Instead, the larger a value the more likely it is that some allergy to that substance occurs. We have cutoff threshold for both skin prick reaction diameter and antibody titres that we use to define what a significant allergy is. Based on positive predictive value. We take 95% as our generally accepted figure.