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BML-ENV-006environmental mouldUSA

Aspergillus fumigatus (m3) IgE Test

The Aspergillus fumigatus (m3) IgE test measures serum concentrations of IgE antibodies specific to this ubiquitous environmental mould, documenting type-I allergic sensitisation. It is central to diagnosing allergic bronchopulmonary aspergillosis in asthma and cystic fibrosis, assessing fungal sensitisation in severe asthma, and monitoring immunological response during antifungal or biologic…

1

Biomarkers

Blood (serum)

Sample

3–5 business days

Turnaround

No

Fasting

What is the Aspergillus IgE (m3) test?

The Aspergillus fumigatus (m3) IgE Test measures serum concentrations of IgE antibodies specific to Aspergillus fumigatus, documenting type-I allergic sensitisation to this common environmental mould. Practitioners order it to investigate suspected allergic bronchopulmonary aspergillosis in patients with poorly controlled asthma or cystic fibrosis, to assess fungal sensitisation in severe asthma, and as part of the differential diagnosis of recurrent wheeze, pulmonary infiltrates, or bronchiectasis that might be fungal-mediated. Because ABPA requires both sensitisation and a characteristic syndrome — elevated total IgE, eosinophilia, central bronchiectasis, and often Aspergillus-positive sputum — the specific IgE is one element of a broader diagnostic framework rather than a stand-alone test. A detectable titre supports fungal involvement, guides antifungal or immunomodulatory therapy, and can be followed serially to monitor disease activity, though absolute levels do not reliably predict clinical severity in every case.

What does the Aspergillus IgE (m3) test measure?

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Aspergillus IgE (m3)(Aspergillus fumigatus-specific Immunoglobulin E)
Range: <0.35 kU/L is considered negative; 0.35–0.69 kU/L equivocal (class 1); ≥0.70 kU/L positive (classes 2–6), with higher classes reflecting greater sensitisation.Optimal: An undetectable or negative result (<0.35 kU/L) indicates absence of measurable IgE sensitisation to Aspergillus fumigatus at the time of testing.kU/L / IU/mL

Aspergillus fumigatus is a ubiquitous saprophytic mould whose airborne conidia are inhaled daily by most individuals without consequence. In susceptible hosts, however, repeated inhalation can prime a type-I hypersensitivity response characterised by production of IgE antibodies directed against fungal antigens. These specific IgE molecules bind to high-affinity receptors on mast cells and basophils; subsequent allergen cross-linking triggers degranulation and the immediate allergic cascade. The m3 allergen designation refers to Aspergillus fumigatus within standardised allergen nomenclature.

Detection of Aspergillus fumigatus-specific IgE confirms type-I sensitisation and is a cornerstone of diagnosing allergic bronchopulmonary aspergillosis (ABPA), a Th2-driven pulmonary syndrome that complicates asthma and cystic fibrosis. Sensitisation also contributes to severe asthma with fungal sensitisation and may be implicated in allergic rhinitis or hypersensitivity pneumonitis when occupational or environmental exposure is high. A positive result indicates immune recognition but does not by itself establish disease; clinical correlation with symptoms, imaging, and pulmonary function is essential.

Why is the Aspergillus IgE (m3) test ordered?

  • Evaluation of suspected allergic bronchopulmonary aspergillosis in patients with asthma or cystic fibrosis who present with worsening wheeze, mucus plugging, fleeting infiltrates, or declining lung function
  • Assessment of fungal sensitisation in adults or children with severe or treatment-refractory asthma, particularly where total IgE is elevated or eosinophilia is present
  • Investigation of recurrent pulmonary infiltrates, central bronchiectasis, or consolidation that raises concern for a fungal hypersensitivity syndrome
  • Occupational or environmental exposure assessment in individuals with respiratory symptoms and exposure to organic dusts, compost, or mould-contaminated environments
  • Pretreatment baseline and serial monitoring during antifungal or biologic therapy for ABPA to assess immunological response
  • Differential diagnosis of chronic cough or sputum production where fungal allergy has not been excluded

Sample collection and turnaround

Sample type

Blood (serum)

Fasting required

No

Collection method

Venipuncture at patient service centre

Turnaround

3–5 business days

Collection notes

Phlebotomy at Quest patient service centre; no special preparation. If the patient is on high-dose corticosteroids, note the dose and duration on the requisition, as this may suppress IgE. Serum is stable refrigerated for several days; avoid repeated freeze–thaw if stored longer.

Specimen requirements

Minimum 0.5 mL serum (gel separator acceptable). Centrifuge promptly and separate from clot. Note any concurrent immunosuppressive therapy.

What can affect Aspergillus IgE (m3) results?

reducesRecent or concurrent corticosteroid therapy

Systemic corticosteroids suppress IgE synthesis and can lower both total and specific IgE levels, potentially masking sensitisation if the test is drawn during high-dose therapy.

reducesImmunodeficiency or immunosuppression

Patients with primary antibody deficiency, HIV, or on immunosuppressive agents may mount a blunted IgE response despite true sensitisation or even invasive disease.

elevatesRecent allergen exposure or exacerbation

Acute exposure and active allergic inflammation can transiently increase specific IgE; serial testing over weeks to months better reflects stable sensitisation status.

variableCross-reactivity with other fungal allergens

Shared carbohydrate and protein epitopes among moulds can cause cross-reactive IgE binding, so a positive result may reflect sensitisation to related fungi rather than Aspergillus fumigatus alone.

variableAge and atopic background

Total and specific IgE production is higher in atopic individuals; children and young adults with a background of allergic rhinitis or eczema are more likely to show detectable fungal IgE.

variableAssay method and calibration

Different immunoassay platforms report results in kU/L or arbitrary units with platform-specific thresholds; serial results should be compared within the same laboratory and method.

What do Aspergillus IgE (m3) results mean?

Elevated

A positive Aspergillus fumigatus IgE (≥0.70 kU/L, class 2 or above) confirms type-I sensitisation. In the appropriate clinical context — asthma or cystic fibrosis with elevated total IgE (often >1000 IU/mL), peripheral eosinophilia, transient pulmonary infiltrates, and central bronchiectasis — it strongly supports allergic bronchopulmonary aspergillosis. Higher classes (3–6) reflect greater antibody concentrations but do not by themselves define disease severity; response to treatment and serial decline are more informative. Isolated sensitisation without the full syndrome may be seen in severe asthma with fungal sensitisation or occupational mould exposure.

Normal

A negative result (<0.35 kU/L) makes IgE-mediated Aspergillus allergy unlikely at the time of testing and argues against ABPA as the cause of respiratory symptoms. However, it does not exclude non-IgE fungal disease (chronic pulmonary aspergillosis, invasive aspergillosis) or sensitisation to other moulds, and a negative test during corticosteroid therapy may be falsely reassuring.

Reduced

An equivocal result (0.35–0.69 kU/L, class 1) suggests low-level sensitisation; repeat testing after interval exposure or correlation with skin-prick testing may clarify. Clinically significant ABPA is unlikely at this level, but evolving sensitisation in high-risk populations warrants follow-up.

Note: Specific IgE must be interpreted alongside total IgE, eosinophil count, imaging, pulmonary function, and microbiological findings. A positive test confirms sensitisation but not disease; conversely, a borderline or negative result in a patient on corticosteroids or with immunosuppression does not rule out fungal involvement. Serial measurement during treatment is more informative than a single value, and declining titres correlate with clinical remission in ABPA.

Frequently asked questions

Total IgE measures all circulating IgE regardless of specificity and is markedly elevated in ABPA, often above 1000 IU/mL. Aspergillus-specific IgE confirms that the elevated response is directed against Aspergillus fumigatus, pinpointing the fungal trigger. Both are required to diagnose ABPA.

How to access the Aspergillus IgE (m3) test

The Aspergillus IgE (m3) reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.

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About this page

Published: October 7, 2026

Last reviewed: October 7, 2026

References:
  1. Agarwal R, et al. International Society for Human and Animal Mycology and European Respiratory Society consensus statement on allergic bronchopulmonary aspergillosis. Eur Respir J. (2013)
  2. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. (2023)
  3. Denning DW, et al. The link between fungi and severe asthma: a summary of the evidence. Eur Respir J. (2006)
  4. Patterson TF, et al. Practice guidelines for the diagnosis and management of aspergillosis: 2016 update by the Infectious Diseases Society of America. Clin Infect Dis. (2016)

This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.