ALEX3 (Allergy Explorer 3) is a multiplex allergy immunoassay that measures specific IgE antibodies to over 300 allergens and allergen components from a single blood draw. It's the most comprehensive allergy blood test currently available in routine clinical practice.
Allergen Categories Covered
Tree Pollens
Birch, alder, hazel, oak, ash, plane, cedar, olive, and all UK-relevant tree species. Molecular components included.
Grass Pollens
Timothy, rye grass, Bermuda grass, and other species — including component testing (Phl p 1, Phl p 5, Phl p 7, Phl p 12).
Weed Pollens
Mugwort, ragweed, plantain, nettle — all seasonal UK and European weed pollens.
House Dust Mites
Dermatophagoides pteronyssinus and D. farinae (the two most common species) plus mite component allergens (Der p 1, Der p 2, Der p 23).
Animal Danders
Cat, dog, horse, rabbit, guinea pig, rat, mouse — plus species-specific molecular components (e.g., Fel d 1 for cat).
Moulds
Alternaria, Cladosporium, Aspergillus, Penicillium — the four most clinically significant moulds in UK environments.
Food Allergens
Peanut, tree nuts (cashew, walnut, hazelnut, almond, pecan, pistachio), milk, egg, wheat, soya, shellfish, fish, sesame, and more — with molecular components.
Insect Venoms
Honeybee (Api m 1) and wasp/yellow jacket (Ves v 5) — including cross-reactive carbohydrate determinants for accurate interpretation.
Molecular Components
PR-10 proteins, lipid transfer proteins, profilins — the cross-reactive components that explain pollen-food syndrome and other cross-reactions.
Why Molecular Components Matter
Traditional allergy tests measure IgE to whole allergen extracts. ALEX3 adds a further layer by identifying sensitisation to individual proteins within those extracts. This matters clinically for two reasons:
- False positives: Some IgE responses are to cross-reactive carbohydrate determinants (CCDs) or profilins — panallergens that create positive results without causing clinical symptoms. ALEX3 identifies these and flags them separately, preventing unnecessary allergen avoidance.
- Risk stratification: For food allergens particularly, the component result changes the risk assessment. Peanut sensitisation to Ara h 2 (seed storage protein) carries a different risk profile from sensitisation to Ara h 8 (PR-10, birch pollen cross-reaction). The treatment and dietary advice differs accordingly.
What the Results Look Like
Results are returned as a detailed allergen profile — each allergen or component is scored by class (0–6) based on the specific IgE level in kU/L. Your GP uses this alongside your clinical history to determine which results are clinically significant, which may represent cross-reactions, and what management is appropriate.
Common Questions
Do I need to stop antihistamines before the test?
No. ALEX3 is a blood test and is unaffected by antihistamine use. Take your regular medication as normal.
Can children have ALEX3 testing?
Yes. ALEX3 is suitable from infancy onwards. The single blood draw is often preferred for young children over multiple skin prick tests.
Can I have ALEX3 if I have eczema?
Yes — and it's particularly useful. Active eczema can make skin prick testing unreliable; the blood test bypasses this entirely.
How quickly are results returned?
Typically 3–5 working days. Your results are reviewed by Dr Raj Dhillon and discussed at a follow-up appointment or via a written summary.
Book ALEX3 Testing at Lambert Medical Practice
The most comprehensive allergy blood test available — 300+ allergens, molecular component analysis, results within days.
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