Questions & Answers

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    ImmunoCAP Rapid. Results direct, clear and simple

ImmunoCAP Rapid is a ready to use test with pre-selected allergens according to symptoms and age. All reagents needed are included in the kit together with a Direction for use. However, questions might arise and here you will find answers to the most frequently asked questions.

 

Sample | Assay Procedure | Interpretation of results | Allergens 

Sample

Q1

Which types of lancets should be used?

Since the blood volume required in the assay is quite high (110 µl), lancets which provide a good blood-flow should be used.

Q2

How critical is the addition of correct blood volume to the Blood Sample Well?

110 µl ± 10 % (100 µl – 120 µl) have been tested and found to work.

Q3

How long can the blood sample be stored in the Blood Sampling Device?

The sample could be stored up to 5 minutes in the Blood Sampling Device without being affected.

Assay Procedure

Q4

If the Assay Device has been stored unprotected without foil pouch, can it be used?

Internal studies have shown that Assay Device is stable for 1 hour at room temperature.

Q5

According to the DFU the first incubation time (separation step and sample incubation) is 5 minutes and after that the Developer Solution should be added. How critical is the first incubation time?

First incubation time has been tested from 5 minutes up to 7 minutes and found to work. The risk of blood leakage will probably increase with time, differing between individual samples and haematocrit levels.

Q6

How critical is the addition of correct volume of the Developer Solution (500 µl)?

Internal studies have shown that results are not affected in the interval of 450 – 550 µl addition of Developer Solution.

Interpretation of results

Q7

If no pink-red Control Lines are seen after the assay time is completed, what do I do?

The Assay Device has not been working properly and patient should be re-tested with a new Assay Device.

Q8

Do the test results have to be read immediately after the assay procedure is completed?

Internal studies show that results are not significantly affected up to one hour after completed assay procedure. However, the risk of blood leakage into the Test Window/Windows will increase with time.

Q9

Why is there a difference in the intensity of the coloured pink-red lines indicating positive test results?

There is an overall relationship between the intensity in the pink-red colour lines and concentration of allergen specific IgE antibodies in samples. However, due to the complexity both in allergen composition and in the immune response in each patient, the relation between colour and IgE antibody concentration may differ from sample to sample.

Q10

Why are sometimes positive test results obtained for t9 (Olive pollen) among the North European population, which usually is not exposed to Olive pollen?

a

One explanation might be different cross-reaction between trees and plants.
Ash (Fraxinus), Lilac (Syringa) and Privet (Ligustrum), trees which are present in the north Europe region, belong to the same family (Oleaceae) as Olive (Olea). Some cross-reactivity between the species could therefore be expected.

Upon Exposure to other tree pollens within the same family, antibodies to common specific allergen structures in the species, have been produced giving a positive t9 results in ImmunoCAP® Rapid, see picture below.

The picture also includes some other examples of possible cross-reaction similar to the example described above. 

b

Antibodies to profilin (a common allergen structure in pollens) might give positive results to some or all pollens included in ImmunoCAP® Rapid.

The exposure and sensitization to t3 – Common silver birch (Betula verrucosa) – might in these case result in positive results to some or all pollen allergens in ImmunoCAP® Rapid, including t3, see picture below. 

 

Q11

Why are sometimes positive test results obtained for d1 (House dust mite Dermatophagoides pterinyssinus) and i6 (Cockroach, Blatella germanica) when there is no known exposure to i6?

Tropomyosin is an allergenic component which might be responsible for a cross-reactivity between Cockroach and House dust mite.

Allergens

Q12

What is the base for choosing the existing allergens on ImmunoCAP® Rapid Wheeze/Rhinitis Child?

The product is developed for children at different ages with allergy-like symptoms such as wheeze and/or rhinitis.

  • The rational for including egg and milk in the profile is that there are reports indicating a link between food sensitization and asthma/wheeze in the youngest children.
  • At increased ages, sensitization to indoor allergens like cat, dog and house dust mite starts to play a more important role.
  • As the child is getting older, outdoor allergens such as pollens from grasses, weeds and trees are becoming more important factors behind allergy-symptoms such as rhinitis and asthma/wheeze.

The selected allergens are suitable for children in both the southern and northern Europe.

Q13

What is the background behind the choice of allergens on ImmunoCAP® Rapid Asthma/Rhinitis Adult?

The product has been developed for adult patients with allergy-like symptoms in the respiratory tract, such as rhinitis and asthma.
In adult allergic patients with respiratory symptoms inhalant allergens are the dominating triggers. There are reports that indoor allergens more often are responsible for allergic asthma and outdoor allergens are more prevalent among allergic patient with upper respiratory tract symptoms.
The chosen allergens are relevant both for Southern and Northern Europe.

Q14

Are the allergen raw materials used in ImmunoCAP® Rapid the same as included in ImmunoCAP® Specific IgE?

The allergen raw materials used in ImmunoCAP® Rapid are basically the same as for the ImmunoCAP® Specific IgE tests, but each individual allergen has been optimized for the ImmunoCAP® Rapid technology.

 

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.