ImmunoCAP Specific IgE

ImunoCAP Specific IgE consists of complete allergens covering over 650 allergens, allergen components covering over 90 components and Phadiatop, a test designed to differentiate between atopic and non-atopic patients.

ImmunoCAP Complete Allergens and ImmunoCAP Allergen Components 
|  ImmunoCAP Phadiatop/Phadiatop Infant

Quantifying IgE antibodies with ImmunoCAP Specific IgE results in accurate evaluation of allergy patients. Here you can learn more about the clinical value, expected test values and the test principle of ImmunoCAP Specific IgE.

Immunodiagnostics offers over 650 different allergens and 90 allergen components for sensitive and precise quantitative detection of allergen-specific IgE antibodies. IgE antibodies appear in human serum and plasma as a result of sensitization to a specific allergen. Measurement of circulating IgE antibodies provides an objective assessment of sensitization to an allergen. In general, low IgE antibody levels indicate a low probability of clinical disease, whereas high antibody levels to an allergen show good correlation with clinical disease. 

The clinical value of quantitative testing

For the clinician

  • IgE antibody development can be detected at an early stage, indicating sensitization, even before clinical symptoms have developed
  • Helps explain the allergy march – the progression of allergic disease
  • Helps explain the allergen load - the allergens that together contribute to allergic symptoms
  • Provides clear directions for disease management

For the laboratory

  • Truly quantitative measuring range from 0.1-100 kUA/L
  • Intra-assay CV (%) comparable to routine clinical chemistry immunoassays
  • Excellent consistency over time, and between countries, systems, labs and persons

Specimen collection and preparation

  • Serum and plasma (EDTA or heparin) samples from venous or capillary blood can be used
  • Collect blood samples using standard procedures
  • Keep specimens at room temperature (RT) for shipping purposes only
  • Store at 2–8 °C up to one week, otherwise store at –20 °C
  • Avoid repeated freezing and thawing

Note: Blood samples for testing ImmunoCAP drugs and venom should be collected during or close to the event, preferably not later than 6 months after exposure. If the test result is negative and an IgE-mediated reaction is still strongly suspected, it is advisable to draw a new sample and repeat the test at 5 to 6 weeks.

Expected test values 

ImmunoCAP Specific IgE detects IgE antibodies in the range 0 to 100 kUA /l, where A represents allergen-specific antibodies. The result is reported quantitatively. In clinical practice, 0.35 kUA /l has commonly been used as a cut-off. A large number of studies have been performed in which the clinical performance of ImmunoCAP Specific IgE tests in allergy diagnosis have been evaluated. Clinical performance is expressed as sensitivity, ranging from 84-95 %, and specificity, ranging from 85-94%. Sensitivity and specificity have been reported from multi-center studies including several hundred patients tested for a range of different allergens. 

 

ImmunoCAP Complete Allergens and ImmunoCAP Allergen Components

An allergy diagnosis is based on a detailed case history, clinical observations and results from IgE testing. Using ImmunoCAP Complete Allergens or ImmunoCAP Allergen Components to determine the presence of IgE antibodies offer a broad range of allergens or allergen components to aid the reliable diagnosis of patients of suspected allergy. 

  • Knowing IgE antibody levels provides guidance in:
  • Tailoring advice to individual patients
  • Complying with target allergen exposure reduction
  • Indicating development of tolerance (food allergy, specific immunotherapy)
  • Facilitating optimised individual medical treatment plans (time and dose)
  • Making appropriate referrals

ImmunoCAP Complete Allergens clinical value 

Results from ImmunoCAP Complete Allergens are used to confirm a suspicion of allergy and to determine the offending allergen or to rule out allergens for which test results are negative. Results can also be helpful in monitoring the IgE levels of antibodies over time. IgE antibody developments can be detected at an early stage, indicating senitization, even before clinical symptoms have developed hereby aiding the identification of patients at risk of:

  • The allergy march – Progression of skin symptoms to respiratory symptoms
  • Exacerbation – Progression of mild symptoms to severe symptoms
  • Chronicity – Progression of recurrent symptoms to persistent symptoms

ImmunoCAP Allergen Components clinical value

From an allergen source, single allergen components can be produced. Sensitization to these components is then measured individually in separate tests, helping to pinpoint, on an exact molecular level, which component the patient is sensitized to. This information provides the basis for a refined diagnosis of the allergy.

Allergen components are proteins that, based on structural similarity, are grouped into different protein families. The consequences of being sensitized to members of these families depend on properties they have in common; they are present in different amounts in the sources and they have different stabilities. Some allergen components are specific and some are cross-reactive.

What does Molecular Allergology add?

  1. Assess the clinical risk for reaction
    Molecular Allergology enables you to draw conclusions on the risk connected with the sensitization. Sensitization to allergen components that are stable may elicit systemic reactions, as well as local reactions, while sensitization to labile components is connected mainly with local reactions.
  2. Explain symptoms due to cross-reactivity
    Symptoms elicited by cross-reacting antibodies can be distinguished from those caused by genuine sensitization, which is important for patient management and for giving adequate avoidance advice. In cases where only cross-reactive sensitization is identified, further testing to find the primary sensitizer should be undertaken.
  3. Identify the right patients for Specific Immunotherapy
    Sensitization to specific allergen components is essential for successful Specific Immunotherapy. By matching patients having a genuine sensitization with an extract from the relevant source, treatment outcome is improved.

 

ImmunoCAP Phadiatop/Phadiatop Infant

Determining the presence of IgE antibodies with ImmunoCAP Phadiatop results in appropriate evaluation of atopic patients. Here you can learn more about the clinical value, expected test values and the test principle of ImmunoCAP Phadiatop/Phadiatop Infant.

ImmunoCAP Phadiatop is a blood test designed to differentiate between atopic and non-atopic patients. Results indicate high or low probability for atopy. A negative result indicates that the symptoms are not caused by common environmental allergens, and the physician may explore other possibilities.

In younger children aged 0-3, allergic sensitization is mostly related to food allergens (such as egg, milk, fish, soybean and peanut) rather than inhalant allergens. However, antibodies to inhalant allergens such as house dust mites and pets can still appear early in life. With this in mind, a combination of Phadiatop and the most common food allergens is recommended when testing children for atopy.

Clinical value

Phadiatop and Phadiatop Infant are assays for the graded determination of atopy with semiquantitative or qualitative results.  

Semiquantitative results

Phadiatop results are expressed as Phadia Arbitrary Units/l (PAU/l) indicating degree of sensitization. A Phadiatop PAU/l value above the limit of quantification indicates that the patient is atopic (positive), i.e. measurable levels of specific IgE antibodies to common inhalant allergens have been detected. A Phadiatop PAU/l value below the limit of quantification indicates that the patient is non-atopic (negative), i.e. the level of specific IgE antibodies is undetectable. Higher Phadiatop PAU/l values indicates a higher degree of sensitization, i.e. higher levels of specific IgE antibodies to common inhalant allergens.

Qualitative results

Phadiatop results are expressed as positive or negative. A positive Phadiatop result indicates that the patient is atopic, a negative result indicates that the patient is non-atopic, i.e. not sensitised to inhalant allergens. In order to determine the concentration of allergen specific IgE antibodies, it is recommended to retest the sample with the appropriate ImmunoCAP Specific IgE allergens.

The following clinical results were obtained from clinical trials including 836 patients with suspected allergy:

Final diagnosis
Atopy/non-atopy
 
ImmunoCAP Phadiatop results  
PositiveNegativeTotal
Atopy 483 38 521
Non-atopy 34 281 315
Total 517 319 836

Sensitivity 93%
Specificity 89%

All tests were run using the 0.35 kU/l specific IgE calibrator as cut off.

Important note

As in all diagnostic testing, a definitive clinical diagnosis should not be based solely on the results of a single test method. A diagnosis should be made by the physician after evaluation of all clinical and laboratory findings.

 

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