The ALEX2 test, also known as the Allergy Explorer, is a modern diagnostic tool designed to identify specific allergens that may be causing allergic reactions. Although not offered on the NHS, it is available privately.
Traditional allergy tests such as skin prick testing can be invasive, time consuming and restrictive. Unlike these, the ALEX2 test utilises advanced molecular technology to deliver precise results. It can be a great first starting point in identifying potential allergens responsible for unexpected symptoms or signs.
Please note that further more specific allergy testing (such as skin prick test or oral food challenges) may still be needed after the ALEX2 test in more complex scenarios.
The ALEX2 testing process involves taking a small blood sample from the patient. The blood is obtained at home, through a small finger prick, similar to the finger prick one would use to check their blood glucose level. This is then sent to the lab and is then analysed to detect the quantity of IgE antibodies.
These antibodies are specific to the allergens tested. From a small volume of blood, The ALEX2 test checks the amount of IgE antibodies to 295 different allergens. These can range from food and pollen to animal dander and dust mites.
This broad initial testing range is particularly useful for individuals who may have multiple or complex allergies.
By identifying the exact allergens responsible for triggering reactions, patients and healthcare providers can develop more effective and targeted treatment plans. It can also provide reassurance to any patients who may have anxiety related to eating certain foods or aeroallergens.
Here are 5 insights to know about the ALEX2 test, if you are considering getting this for you or your family.
Insight 1: Comprehensive Allergy Panel
The ALEX2 test evaluates specific IgE against nearly 300 allergens, including 117 allergen extracts and 178 molecular allergens.
Here is the full list of ALEX2 allergens, but broadly they come under the following groups:
| Allergen Group | Examples |
|---|---|
| Pollens | Tree pollens (birch, oak, olive), Grass pollens (ryegrass, timothy grass), Weed pollens (ragweed, mugwort) |
| Mites | House dust mites (Dermatophagoides pteronyssinus, Dermatophagoides farinae), Storage mites (Acarus siro) |
| Animal Allergens | Pet dander (cat, dog, horse), Farm animal allergens (cow, pig) |
| Insect Venoms | Bee venom, Wasp venom, Cockroach allergens |
| Moulds and Yeasts | Indoor moulds (Aspergillus, Penicillium), Outdoor moulds (Cladosporium, Alternaria) |
| Food Allergens | Nuts and seeds (peanuts, almonds, walnuts), Milk and eggs (cow’s milk, hen’s egg), Fruits and vegetables (apples, carrots, tomatoes), Legumes (soybeans, lentils), Fish and seafood (cod, shrimp), Spices (mustard, sesame), Meat (beef, chicken) |
| Latex | Natural rubber latex allergens |
| Microorganisms and Spores | Various bacteria and fungal spores associated with allergies |
Insight 2: Easy to understand, colour coded report
The report issued by our lab starts off with an initial overview of your test results. This includes the above allergen groups, with a subsequent score of 0 to 4.
ALEX2 sample report showing IgE scores and colour legend.
As you can see in this table, a score of 0 shows undetectable IgE antibodies to an allergen, and a higher score shows more of the allergen antibodies present in your blood sample.
The higher the score, the more allergen antibodies are present. This also tends to correlate to a higher potential allergy. There are of course exceptions to this, which would require a more thorough consultation.
Insight 3: Summary and detailed report
The first page of the report always includes a summary of the score of each allergen group.
The following 8 pages then go on to give you a quantifiable result for each allergen in more detail.
Milk Allergy
For example, milk allergy is often to one or a combination of the following four proteins: Bos d_milk, Bos d 4 (also known as α-Lactalbumin), Bos d 5 (also known as β-Lactoglobulin) or Bos d 8 (also known as Casein). The presence or absence of IgE antibodies to these different proteins can be useful in understanding the type of allergy you have to milk and whether you may outgrow it or not.
Studies suggest that children sensitised to multiple milk proteins, especially casein (Bos d 8), may have a lower likelihood of outgrowing their milk allergy compared to those sensitised to a single protein such as β-lactoglobulin.
Insight 4: Cross Reactive allergens identified
The ALEX2 test also detects cross reactive allergy syndromes. These include pollen-food or latex-food cross reactivity.
The table below shows more information for each group and what the different proteins represent.
| Cross-reactive Allergen Family | Description |
|---|---|
| Polcalcin | Proteins found in pollen causing cross-reactivity between different types of pollens. |
| Profilin | Plant proteins causing cross-reactivity between various pollen, fruits, and vegetables. |
| PR-10 | Pathogenesis-related proteins in plants causing cross-reactivity, commonly seen in birch pollen-fruit syndrome. |
| Ole e 1 Family | Major allergens from olive pollen causing cross-reactivity with other plant-derived allergens. |
| LTPs (Lipid Transfer Proteins) | Proteins in many fruits, vegetables, nuts, and cereals causing severe allergic reactions and cross-reactivity. |
| Storage Proteins | Proteins stored in seeds and nuts causing cross-reactivity among different seeds and nuts. |
| Lipocalins | Proteins in animal dander that are responsible for cross-reactivity between different animal allergens. |
| NPC2 | Minor allergens that could be causing cross-reactivity among various animal dander. |
| Serum Albumin | Proteins in blood causing cross-reactivity between different animal-derived foods and allergens. |
| Parvalbumin | Proteins in fish that could be causing cross-reactivity among different fish species. |
| Tropomyosin | Proteins in shellfish and insects causing cross-reactivity between shellfish and insect allergens. |
| CCD (Cross-reactive Carbohydrate Determinants) | Carbohydrate structures in plants and insects causing cross-reactive allergic reactions. |
| Uteroglobin | Minor allergens causing cross-reactivity among different animal dander. |
| Arginine kinase | Proteins in various invertebrates including shellfish and insects, leading to cross-reactivity. |
Insight 5: Facilitates Personalized Immunotherapy
The ALEX2 Allergy Explorer test significantly enhances the ability to tailor immunotherapy to individual patients by providing detailed and precise allergen profiles. The comprehensive profiling allows for a detailed understanding of a patient’s sensitization patterns.
By pinpointing exactly which allergens a patient is sensitized to, we can design tailored immunotherapy regimens that target these specific allergens. This targeted approach increases the effectiveness of the treatment while minimizing exposure to unnecessary allergens.
As the ALEX2 test includes cross-reactive carbohydrate determinant (CCD) inhibitors, this increases the accuracy of our results by reducing non-specific reactions. This helps in distinguishing true sensitizations from cross-reactivities, ensuring that immunotherapy is focused on clinically relevant allergens
Ultimately, please remember that the diagnosis of an allergy can only be made by a clinician based on the presence of both symptoms and sensitisation.
A test such as ALEX2 can play a major part in identifying sensitisation to the different allergen groups. However, we would always also recommend a consultation with a clinician to discuss the implications of your ALEX2 test results, and whether you have a true allergy or not.
