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If you have asthma that flares in damp weather, eczema that won't quiet down, or persistent congestion that no one can quite explain, mold may be part of the picture. This blood test looks for an immune signal showing whether your body has been sensitized to Cladosporium herbarum, one of the most widespread outdoor molds in the world.
Knowing your result helps you connect symptoms to a specific trigger you can avoid, monitor, or treat with allergen-targeted therapy. It is most useful when allergy testing has been incomplete or when standard panels skip mold entirely.
The test measures Cladosporium herbarum IgE (immunoglobulin E), an antibody your immune system makes when it has been sensitized to this mold. IgE is produced by specialized immune cells called B cells and plasma cells, then circulates in your blood and binds to allergy cells (mast cells and basophils) waiting to release histamine on the next exposure.
A positive result means your immune system recognizes Cladosporium and is primed to react. It does not automatically mean you have a clinical mold allergy. The clinical interpretation depends on whether you have symptoms when exposed.
Mold sensitization shows up most clearly in asthma. In a school-aged population, children with elevated mold-specific IgE (above 0.35 IU/mL, including IgE to Cladosporium) had about six times the risk of asthma compared with non-sensitized peers. Most of those affected were boys exposed to indoor dampness.
In severe asthma, mold matters even more. Roughly 24% of severe asthmatics test positive for fungal sensitization on Cladosporium and related molds, and identifying this group changes how the disease is managed. Severe asthma with fungal sensitization (SAFS) tends to start earlier, requires more oral steroids, and in pediatric studies has been linked to a steroid-resistant inflammation pathway driven by an immune messenger called IL-33.
In adults with atopic dermatitis (eczema), positive IgE to Cladosporium components (Cla h and Cla h 8) tracks with disease severity. Higher IgE classes show up more often in patients whose eczema is worse and in those who also have asthma. The test does not diagnose eczema, but it can help explain why standard treatments are not getting the disease under control.
In chronic rhinosinusitis, mold sensitization is uncommon overall, but Cladosporium IgE positivity occurred in about 6.3% of post-surgery cases and contributed to broader allergic profiles. Some people with mold-triggered rhinitis have negative blood and skin tests for Cladosporium yet still react on direct nasal challenge. This pattern, called local allergic rhinitis, means a normal blood result does not always rule out mold-driven nasal symptoms.
There is no single universal reference range for Cladosporium IgE. Different labs and assays use different cutoffs, and results are typically reported as both a numeric value and a class. The thresholds below come from published research using ImmunoCAP and ALEX2 component-resolved testing in mixed adult and pediatric allergy populations. Use them as orientation, not a fixed target. Your lab may report different units or class boundaries.
| Class | Range (kUA/L) | What It Suggests |
|---|---|---|
| Class 0 | Below 0.30 | No sensitization detected |
| Class 1 | 0.30 to 1.00 | Low-level sensitization |
| Class 2 | 1.00 to 5.00 | Moderate sensitization |
| Class 3 to 4 | Above 5.00 | High to very high sensitization |
Sources: ALEX2 Allergy Explorer class system; schoolchildren EIA cutoff of 0.35 IU/mL (Taskinen 2001). Compare your results within the same lab over time for the most meaningful trend.
Cladosporium sensitization is real but uncommon in the general population. In a US dataset of more than 1.6 million tested patients, 11.1% were positive. In Finnish allergy clinic patients, only 2.7% were positive on skin testing. In schoolchildren, mold-specific IgE was elevated in roughly 5% overall. Higher rates show up in selected groups: severe asthmatics, children with eczema, and patients exposed to damp environments.
A single result tells you whether you are sensitized today. It does not tell you how your immune response is changing. Specific IgE levels can shift with allergen exposure, allergen immunotherapy, age, and resolving atopy, so retesting matters when you are making decisions based on this number.
Get a baseline now. If you start allergen avoidance measures, immunotherapy, or other allergy-directed treatment, retest in 6 to 12 months to see whether your IgE is moving. Then retest annually if you are managing an active mold-related condition. Trends within the same lab are more informative than any single absolute value.
Two findings can seem to contradict each other. Some immunotherapy trials in Cladosporium-allergic children showed clear clinical improvement (less medication, less bronchial reactivity) even though serum IgE often went up before drifting back toward baseline. The resolution is that this test is a sensitization marker, not a severity meter. The number tells you whether your immune system recognizes the mold; symptom control depends on a broader set of factors, including how your IgG and regulatory immune responses change. Do not interpret a stable or briefly higher IgE during treatment as a treatment failure.
If your Cladosporium IgE is positive, the next step depends on your symptoms. With ongoing asthma, eczema, or rhinitis, an allergist can connect this result to a complete allergen profile, including dust mite, pet dander, pollens, and other molds, and assess whether allergen-specific immunotherapy is appropriate. If you have severe or steroid-dependent asthma, this result fits the SAFS pattern and warrants review by a pulmonologist familiar with fungal sensitization.
If you have no symptoms, a positive result alone does not require treatment. Use it as orientation: reduce indoor dampness, address visible mold in your home, and recheck if you develop new respiratory or skin symptoms. If you have nasal symptoms but a negative result, ask about nasal allergen challenge testing, which can detect local allergic rhinitis that blood tests miss.
Evidence-backed interventions that affect your Cladosporium Herbarum Mold IgE level
Cladosporium Herbarum Mold IgE is best interpreted alongside these tests.