"ImmunoCAP rapid wheeze/rhinitis" test for allergy diagnosis in children with respiratory symptoms

Recurrent respiratory symptoms are very frequent in childhood.

In this study, the value of an in vitro diagnostic device testing 10 common allergens, the ImmunoCAP® rapid wheeze/rhinitis Child, was investigated for the primary evaluation of allergy.

The investigators carried out their usual diagnostic work-up including IgE tests. The ImmunoCAP® Rapid test was performed with capillary whole blood.

The physicians' diagnostic conclusions on major triggering allergens were compared to the ImmunoCAP® Rapid test results. The sensitivity of the ImmunoCAP® Rapid test for unveiling allergic disease was 92% and the specificity 97%.

For children with asthma falling, sensitivity was 100% and specificity 100%, for children with rhinitis sensitivity was 93% and the specificity 100%.

The investigators concluded that ImmunoCAP® Rapid test was an accurate test, with high specificity, for diagnosing allergy in children with recurrent respiratory diseases in primary care settings.

ImmunoCAP Immunoassay

The ImmunoCAP method was developed by Phadia. It utilizes a “sandwich” ELISA technique:

1. The ImmunoCAP sponge has allergen bound to it and serves as the first piece of bread ("bottom half").

2. Patient serum is added and specifc IgE to that allergen binds to the allergen on the sponge - this is the "meat" of the ELISA sandwich.

3. All of the unbound protein is washed away abd anti-IgE is added - this binds to the sIgE that was captured by the sponge in step two. The anti-IgE conjugate is the "second piece of bread" ("top half").

Allergen-specific IgE levels are not comparable between different laboratory methods - for example, ImmunoCAP vs. DPC Immulite 2000. Predictive values of specific IgE levels published in the literature for management of food allergies are based on studies using the ImmunoCAP assay. These predictive values cannot be applied to specific IgE levels from other assay systems.

References:
The ImmunoCAP® rapid wheeze/rhinitis child test is useful in the initial allergy diagnosis of children with respiratory symptoms. Philippe A. Eigenmann et al. Pediatric Allergy and Immunology, 06/2009.

Phadia Announces FDA Clearance of ImmunoCAP Rapid - "first point-of-care test" to assist in the diagnosis of allergy
Allergy blood testing: A practical guide for clinicians - CCJM review, 2011.

Image source: ImmunoCAP Rapid.