Contents
What is the ALEX³ Allergy Test?
The ALEX³ (Allergy Xplorer 3) is the latest generation of the most advanced multiplex molecular allergy blood test available in private practice in the UK. Developed by MacroArray Diagnostics (MADx) in Vienna, Austria, it uses chip-based macroarray technology to simultaneously measure allergen-specific IgE (sIgE) antibodies to over 300 allergens and molecular allergen components from a single small blood sample.
Unlike standard allergy blood tests that measure IgE to whole allergen extracts (e.g. “peanut” or “grass pollen” as a whole), ALEX³ goes further — it identifies which specific proteins within each allergen source are responsible for your immune response. This distinction is clinically transformative: it determines whether a positive result represents genuine allergy, harmless cross-reactivity, or risk of severe systemic reactions.
At the London Allergy and Immunology Centre, all ALEX³ results are reviewed and clinically interpreted by a consultant allergist — never by algorithm alone. Results are placed in the context of your full clinical history, symptoms, and any other investigations, to produce a meaningful, personalised diagnostic report.
Recommended in current guidelines
The EAACI 2025 guidelines on IgE-mediated food allergy recommend that component-resolved diagnostics (CRD) should be used as standard to distinguish primary sensitisation from cross-reactive responses, and to guide immunotherapy selection. ALEX³ is one of the platforms that delivers CRD in clinical practice.
How ALEX³ Works — The Technology
ALEX³ uses a solid-phase nano-bead macroarray — a chip onto which hundreds of allergens and molecular components are individually immobilised. When a patient’s blood sample is applied, any IgE antibodies present bind to their corresponding allergen spots. The result is then read quantitatively, producing a precise sIgE level for each of the 300+ allergens simultaneously.
Macroarray chip platform
Allergens and molecular components are bound to a microarray chip. Each position on the chip corresponds to a specific allergen or component. The patient’s serum is incubated across the chip — IgE antibodies bind where sensitisation exists.
Quantitative ELISA readout
Binding is detected and quantified using an enzyme-linked fluorescent assay. Results are expressed as quantitative sIgE concentrations (kU/L), with total IgE also measured simultaneously. Fully automated processing eliminates inter-laboratory variability.
CCD inhibition — reducing false positives
Cross-reactive carbohydrate determinants (CCDs) are shared sugar structures present in many plant pollens and foods. They can produce false-positive IgE results in standard tests. ALEX³ incorporates CCD inhibition within the assay, substantially reducing clinically irrelevant cross-reactive signals and improving specificity.
RAPTOR software analysis
Results are processed by MADx’s proprietary RAPTOR software and stored on a GDPR-compliant cloud server. The allergen panel is continuously updated using real-world data from over 400,000 tests performed across 90+ countries, ensuring the panel reflects clinically current sensitisation patterns.
What Is New in ALEX³ — 2025 Update
ALEX³ replaces ALEX2 and was designed using data from nearly 400,000 real-world ALEX2 test results collected between 2020 and 2023 from over 90 countries. This big-data approach identified which allergens were clinically underrepresented, which were redundant, and which new allergens warranted addition based on emerging sensitisation patterns. A landmark 2025 paper (Sturm et al., Allergy) describes the evidence basis for ALEX³’s design in detail.
Expanded to 300 allergens
ALEX³ includes 218 molecular components (up from 178 in ALEX2) and 82 allergen extracts, covering 145 allergen sources. Importantly, 107 of the molecular components are unique to ALEX³ and not available on any other commercial platform — giving the widest molecular coverage available.
52 new allergens added
New additions include: alpha-gal (the tick-borne red meat allergy marker), cyclophilins (important pan-allergens in mould and latex cross-reactivity), new crustacean and shellfish components, coconut, pine nut, maize pollen, oak tree pollen, golden hamster dander, and bald-faced hornet venom.
Obsolete allergens removed
Allergens with low global prevalence and limited clinical utility, and those found to be redundant through real-world data analysis, were removed. This makes the panel more clinically focused and improves signal-to-noise in results interpretation.
Improved automated processing
Full automation via the MAX9k or MAX45k systems reduces processing variation and turnaround time. Results are available typically within 5–7 working days of sample receipt at the laboratory.
Why Component-Resolved Diagnostics (CRD) Changes Everything
Standard allergy tests tell you what you react to. Molecular CRD tells you why — and whether that reaction is clinically important. The same positive result on a conventional test can mean very different things depending on which molecular component is driving it.
The broader principle: Sensitisation to a food or pollen does not equal clinical allergy. In the UK, 11.8% of school-aged children test positive for peanut IgE on conventional tests, yet only 2.6% have true peanut allergy when properly assessed. CRD prevents unnecessary dietary restriction, anxiety, and missed diagnoses — and ensures that those who genuinely need treatment receive it.
Who Benefits from ALEX³ Testing?
ALEX³ is particularly valuable in the following clinical scenarios. Your consultant will advise whether it is the most appropriate test for your specific situation.
Multiple or Overlapping Allergies
Patients sensitised to many foods, pollens, or environmental allergens simultaneously — where standard singleplex tests would require many separate blood draws and provide less contextual information. One ALEX³ sample provides the complete sensitisation map.
Unclear or Conflicting Previous Results
Patients with positive IgE tests who have never had a clear reaction, or those told they are allergic to many foods but finding strict avoidance difficult or symptoms persist despite avoiding them. CRD clarifies what is genuinely clinically relevant.
Confirming Peanut or Nut Allergy Severity
Ara h 2 level on ALEX³ is the most accurate single marker of true peanut allergy severity available. It guides adrenaline auto-injector prescription, food challenge decisions, and OIT (Palforzia®) eligibility assessment.
Pre-Immunotherapy Workup
Before starting allergen immunotherapy (SCIT, SLIT, or venom VIT), identifying the true primary sensitiser (rather than a cross-reactive species) ensures the most appropriate allergen extract is selected — maximising effectiveness and avoiding ineffective treatment.
Polysensitised Adults & Children
Adults with hayfever who also react to certain fruits and vegetables (oral allergy syndrome); individuals with both eczema and multiple food sensitivities; complex paediatric allergy presentations. ALEX³ provides the holistic sensitisation picture needed to manage these cases.
Unexplained Delayed Reactions to Meat
ALEX³ now includes alpha-gal, enabling testing for the tick-triggered red meat allergy (alpha-gal syndrome / AGS) in a single panel — see dedicated section below.
Monitoring Response to Immunotherapy
ALEX³ can be used to track changes in molecular sensitisation profiles during allergen immunotherapy, providing objective evidence of immune tolerance induction — particularly relevant during peanut OIT and respiratory allergen SCIT/SLIT.
Key Allergen Components on ALEX³ — Clinical Examples
The following illustrates how molecular component information from ALEX³ translates into concrete clinical decisions. This is not an exhaustive list of the 300 components included.
| Allergen Source | Component | Protein Family | Clinical Significance |
|---|---|---|---|
| Peanut | Ara h 2 | 2S albumin | Best single marker of true peanut allergy. Predicts risk of severe reactions / anaphylaxis. High specificity. |
| Peanut | Ara h 8 | PR-10 (birch cross-reactive) | Cross-reactivity with birch pollen. If isolated, not true peanut allergy — oral allergy syndrome only. Not anaphylaxis risk. |
| Birch pollen | Bet v 1 | PR-10 | Primary birch sensitiser. Also drives OAS to apple (Mal d 1), hazelnut (Cor a 1), carrot, cherry. Best target for birch SCIT/SLIT. |
| Grass pollen | Phl p 1, Phl p 5 | Major grass allergens | True primary grass pollen sensitisation. Excellent candidate for grass pollen SLIT or SCIT immunotherapy. |
| House dust mite | Der p 1, Der p 2 | Major mite allergens | Primary HDM sensitisation confirming candidacy for HDM SCIT or SLIT immunotherapy. |
| Cat | Fel d 1 | Major cat allergen | True cat allergy marker. Positive Fel d 1 confirms genuine cat sensitisation for AIT candidacy. |
| Bee venom | Api m 1, Api m 10 | Phospholipase A2; Icarapin | True bee venom sensitisation markers. Distinguishes genuine bee allergy from CCD false positivity to wasp. |
| Wasp venom | Ves v 5 | Antigen 5 | Wasp-specific major allergen. Confirms genuine wasp sensitisation, guiding VIT selection. |
| Red meat / tick (new) | Alpha-gal (α-Gal) | Oligosaccharide epitope | Marker of alpha-gal syndrome — delayed allergy to red meat triggered by tick bite. New in ALEX³. See section below. |
Alpha-Gal Syndrome — New on ALEX³ & Now Testable in the UK
Alpha-gal syndrome (AGS) is a novel and increasingly recognised form of IgE-mediated allergy to the carbohydrate molecule galactose-α-1,3-galactose (α-Gal), found in the tissues of most mammals except humans and other primates. It is triggered by sensitisation through tick bites — specifically, tick saliva contains α-Gal which drives IgE production in some individuals. Once sensitised, eating red meat (beef, pork, lamb) causes a characteristically delayed allergic reaction 3–6 hours after ingestion.
Symptoms of Alpha-Gal Syndrome
- Urticaria (hives), angioedema, or anaphylaxis occurring 3–6 hours after eating red meat
- Nausea, abdominal cramps, or diarrhoea after meat consumption
- Reactions to beef, pork, lamb, venison, and other mammalian meats
- Some patients also react to dairy products or gelatine
- History of tick bites (though many patients do not recall specific bites)
Why AGS Is Often Missed
The delayed onset (3–6 hours, unlike most food allergies which occur within minutes) means patients and clinicians often do not connect symptoms to the preceding meal. Reactions may also be triggered or worsened by cofactors such as exercise, alcohol, or NSAIDs taken after eating — making the pattern even harder to identify without awareness of AGS. The delayed-onset pattern is unique among IgE-mediated food allergies.
Testing & Management
Specific IgE to alpha-gal is now included in ALEX³, making it testable within our standard molecular allergy panel. Where AGS is suspected, your consultant may recommend a standalone alpha-gal IgE alongside the full ALEX³ panel. Management involves avoidance of mammalian meats; dairy avoidance is assessed on an individual basis. Alpha-gal is not currently listed as one of the 14 major UK food allergens requiring mandatory labelling.
ALEX³ vs Other Allergy Tests — How It Compares
| Test Type | What It Measures | Molecular CRD? | Best Used For | Limitations |
|---|---|---|---|---|
| ALEX³ | sIgE to 300 allergens & molecular components simultaneously | Yes — 218 components | Comprehensive first-line sensitisation profiling; complex multi-allergen presentations; pre-immunotherapy workup; distinguishing allergy from cross-reactivity | Blood test only — cannot replace skin testing for some indications; requires consultant interpretation |
| ISAC (112 components) | sIgE to 112 molecular components | Yes — 112 components | Polysensitised patients; CCD discrimination; established molecular platform | Fewer components than ALEX³; no extracts included; semi-quantitative for some results |
| Standard specific IgE (singleplex RAST) | sIgE to individual allergen extracts — one at a time | Limited — some single-allergen component tests available | Confirming a single specific allergen when history is clear; quantitative follow-up of a known sensitisation | Cannot distinguish allergy from cross-reactivity without additional components; one at a time — many draws for complex presentations |
| Skin prick test (SPT) | Immediate skin wheal reaction to allergen extracts | No | First-line in-clinic testing; rapid results within 20 minutes; safe from birth; can use fresh foods | Cannot identify specific proteins; antihistamines must be stopped; not suitable in severe eczema or dermographism |
| IgG “food intolerance” tests | IgG antibodies to foods | No | Not validated. Not recommended by EAACI, BSACI, or NICE. | IgG to foods is a normal immune response to eating; results are not clinically meaningful. Can cause harmful dietary restriction. |
The ALEX³ Testing Process at Our Clinic
Consultant Consultation
Before ordering ALEX³, your consultant will take a detailed clinical history of your symptoms, reaction patterns, dietary habits, and prior test results. This guides interpretation and determines whether ALEX³ alone is sufficient or whether additional tests (skin prick, food challenge) are also needed.
Blood Sample Collection
A small blood sample (serum) is taken — either by our trained nurses at the clinic or, for at-home testing, via a postal finger-prick or venous collection kit. Antihistamines do not need to be stopped before a blood test. No fasting is required.
Laboratory Analysis — 5–7 Working Days
The sample is sent to our specialist laboratory for ALEX³ processing. The macroarray chip is run on the automated MADx platform; quantitative sIgE results are generated for all 300 allergens simultaneously, alongside total IgE. GDPR-compliant cloud storage ensures result security.
Consultant Review & Interpretation — The Critical Step
Your consultant reviews the full ALEX³ results in the context of your clinical history. Positive results are assessed for their clinical significance — which are primary sensitisations, which are cross-reactive, which require action. A personalised written report and management plan is produced. Results are accessible securely via the Carebit patient portal.
Follow-Up & Treatment Plan
A follow-up consultation reviews your results in detail — covering which allergens matter, what to avoid, whether further tests (food challenge, skin prick) are needed, whether immunotherapy is appropriate, and any medication or emergency planning required. A detailed clinic letter is sent to you and, with consent, to your GP.
ALEX³ At-Home Postal Testing — Available Across the UK
Patients across England, Scotland, Wales, and Northern Ireland can access the full ALEX³ molecular allergy test without travelling to London — via our UK-wide at-home postal testing service. The same test, the same laboratory, the same consultant review.
Order online
Purchase the ALEX³ test online and a home sample collection kit is sent to your address with full instructions.
Collect sample
A finger-prick kit is provided (a local phlebotomy service may be recommended for very young children or those who prefer a venous draw).
Post sample
Return the sample via the pre-paid, temperature-controlled packaging. Processed at our specialist laboratory within 5–7 working days of receipt.
Consultant review
Results are reviewed by a consultant and a video consultation arranged to discuss findings, their meaning, and next steps.
Important: ALEX³ results must always be interpreted by a specialist. A positive result on any component does not automatically mean avoidance is required — clinical context determines whether each positive is clinically relevant or not. Always arrange a consultant review following your results, whether testing at home or in clinic. International samples are accepted — please contact us to discuss logistics before purchase.
Frequently Asked Questions
Important Notice
All ALEX³ results must be interpreted by a qualified allergy consultant in the context of a full clinical history. A positive sIgE result does not confirm clinical allergy without specialist review. Consultations and prescriptions are subject to a separate fee. In a medical emergency, call 999.
References
- Sturm GJ, et al. Big data-driven evolution of a diagnostic multiplex IgE-test: enhancing accuracy and efficacy in allergy diagnostics. Allergy. 2025. doi:10.3390/allergies5020012 (PMC12072476)
- Santos AF, Riggioni C, et al. EAACI Guidelines on the Management of IgE-mediated Food Allergy. Allergy. 2025;80(1):1–28. doi:10.1111/all.16345
- Hemmings O, Du Toit G, Radulovic S, Lack G, Santos AF. Ara h 2 is the dominant peanut allergen despite similarities with Ara h 6. J Allergy Clin Immunol. 2020;146(3):621–631.
- MacroArray Diagnostics (MADx). ALEX³ Allergy Xplorer — product information and instructions for use. Vienna, Austria. 2024/2025. www.macroarraydx.com
- Ampath Pathology. Introducing ALEX3 Allergy Xplorer. Laboratory Update 68. March 2026.
- Commins SP, et al. Delayed anaphylaxis, angioedema, or urticaria after consumption of red meat in patients with IgE antibodies specific for galactose-α-1,3-galactose. J Allergy Clin Immunol. 2009;123(2):426–433.
- Allergyclinic.co.uk. Alpha-Gal Syndrome: The Tick-Borne Red Meat Allergy Hits the UK. February 2026.
- Sturm GJ, Varga EM, Roberts G, et al. EAACI guidelines on allergen immunotherapy: Hymenoptera venom allergy. Allergy. 2018;73(4):744–764.
Page reviewed: June 2026 | London Allergy and Immunology Centre | privateallergy.uk