Cladosporium Herbarum (Cla h 8) IgE

If your asthma flares in late summer, your eczema worsens when the air turns damp, or you live with allergy symptoms that don't line up with pollen or pet exposure, mold may be part of the picture. This test looks for an immune signature pointing at one specific protein from Cladosporium herbarum, one of the most abundant outdoor molds in the world.

Knowing your result gives you a concrete answer about whether your immune system has flagged this mold as a target. That information matters most when your symptoms are severe, hard to explain, or you are considering longer-term steps like allergy immunotherapy.

What This Test Actually Measures

The test measures IgE (immunoglobulin E, an antibody class involved in allergic reactions) in your blood that specifically recognizes Cla h 8 (the eighth officially catalogued allergen from Cladosporium herbarum). Cla h 8 is a fungal enzyme called NADP-dependent mannitol dehydrogenase, which is recognized by IgE antibodies in roughly 57 percent of people with Cladosporium allergy and is considered one of the major allergens of this mold.

Detecting this antibody means your immune system has been trained to react to that exact protein. That state is called sensitization. Sensitization is not the same thing as having symptoms, but it is the immune setup that makes allergic reactions possible when you encounter mold spores in the air.

Because Cla h 8 is a single, defined protein rather than a crude mold extract, this measurement is part of what allergists call component-resolved testing. The result helps map your sensitization more precisely than older tests that mix many fungal proteins together. Cla h 8 component testing is not yet part of routine clinical practice in most settings and is primarily available through multiplex platforms like ALEX 2.

Why a Mold Test Belongs in a Modern Allergy Workup

In a US dataset of more than 1.6 million people tested for fungal allergens, about 11 percent had detectable IgE to Cladosporium herbarum. A separate Ukrainian dataset using a molecular panel that includes Cla h 8 reported a similar range of sensitization to this specific component.

Sensitization to different fungal proteins tends to develop independently, which is why a precise component test can add information that a generic mold screen may miss. A negative result for a broad Cladosporium extract does not always rule out sensitization to Cla h 8, since the two measurements capture overlapping but distinct slices of the immune response.

Atopic Dermatitis Severity

In 100 adults with atopic dermatitis evaluated using the ALEX 2 molecular panel, sensitization to Cla h 8 was significantly linked to disease severity, and people who tested positive were significantly more likely to have coexisting asthma than people who did not.

For someone with stubborn eczema that does not respond well to standard skincare and topical treatment, a positive Cla h 8 result reframes the picture. It suggests the immune system is reacting to a year-round outdoor exposure that flares with humidity, decaying leaves, and damp indoor environments. That information can shape both your environmental strategy and your conversations about more advanced treatment.

Asthma and Wheeze

In a multicenter study of 1,132 adults with current asthma from the European Community Respiratory Health Survey, sensitization to airborne molds (Alternaria alternata or Cladosporium herbarum) was strongly tied to more severe asthma, with an odds ratio of about 2.16 for severe versus mild asthma after adjustment, independent of other common allergen sensitizations. An older pediatric clinic dataset has also reported Cladosporium-specific IgE as one of the stronger predictors of asthma in children, though that finding comes from a single, narrow study and should be interpreted cautiously.

In one study of adults with severe asthma, about 24 percent had Cladosporium sensitization specifically, and broader literature suggests fungal sensitization overall affects at least a third of people with severe asthma. Identifying it matters because subgroups like severe asthma with fungal sensitization or allergic bronchopulmonary disease may respond to specific antifungal strategies. If your asthma is severe, persistent, or hard to control, knowing your fungal sensitization status is useful information your standard inhaler regimen cannot reveal.

Allergic Rhinitis and Polysensitization

Cla h 8 sensitization rarely shows up alone. It tends to appear alongside other allergen sensitivities, and people in the highest categories of polysensitization carry the heaviest burden of allergic disease. A positive result is most useful when interpreted as one piece of your broader allergy profile, not as a stand-alone explanation for any specific symptom.

Reading a Positive Result Without Overinterpreting It

A detectable Cla h 8 IgE level confirms sensitization, but sensitization is a setup, not a diagnosis. Whether your immune reaction actually drives symptoms depends on how much mold you are exposed to, what other allergens you react to, and how your body responds in real life.

In a large Finnish study of 7,927 people with allergy symptoms, sensitization to Cladosporium herbarum was uncommon and often clustered with multiple other sensitizations, so a positive result on its own was not a confident explanation for symptoms in that population. Cladosporium components, including Cla h 8, also tend to produce lower antibody levels than some other fungal allergens, so values often look modest even when they are clinically real.

The practical takeaway: a positive result is a prompt to look further, not a final answer. Pair it with your symptom history, your environment, and ideally a discussion with an allergist before making major changes.

When Results Can Be Misleading

A few situations can make a single Cla h 8 IgE reading harder to interpret:

• Sensitization without symptoms: in a birth cohort, 39 percent of children sensitized to Alternaria or Cladosporium by age 4 had no allergic symptoms. A positive test does not automatically mean you are allergic in the clinical sense.
• Negative blood test, real symptoms: in some people with chronic nasal symptoms, blood and skin tests are negative but nasal challenge with mold extracts is positive, a pattern called local allergic rhinitis. A negative Cla h 8 IgE does not fully rule out clinically relevant mold sensitivity.
• Method differences: older laboratory methods often miss antibodies that newer molecular assays detect. Comparing results across different test platforms can be misleading.
• Polysensitization context: Cla h 8 sensitization rarely sits alone, so a positive result usually needs to be interpreted alongside the rest of your allergen profile rather than in isolation.

Tracking Your Trend Over Time

A single number tells you whether you are sensitized today. Tracking the trend can show whether that sensitization is intensifying, fading, or holding steady. IgE patterns can shift with age, exposure, and treatment, though no formal guideline specifies how often Cla h 8 itself should be retested.

A reasonable approach is to get a baseline now, and consider repeating the test if you are actively changing your environment, starting allergy treatment, or trying to confirm a clinically suspected mold trigger. If you start allergen immunotherapy specifically targeted at Cladosporium, repeated measurements can show whether the treatment is shifting your antibody profile. A randomized trial in children with mold-induced asthma found that immunotherapy with a standardized Cladosporium herbarum preparation reduced specific IgE and increased a protective antibody class, alongside clinical improvement.

What an Out-of-Pattern Result Should Make You Do Next

If your Cla h 8 IgE is positive and you have meaningful allergy symptoms, the next step is not to retest immediately. It is to widen the workup. A focused mold component panel that includes Alternaria, Aspergillus, Penicillium, and Malassezia components can reveal whether you have a broad fungal sensitization pattern or one driven mainly by Cladosporium. Total IgE provides context for how active your overall allergic immune system is, and a standard inhalant allergen panel maps your reactions to dust mites, pets, and pollens that may matter more than mold.

If your asthma is severe, recurrent, or steroid-dependent, your positive result is a reason to involve a pulmonologist or allergist familiar with severe asthma with fungal sensitization. If your eczema is severe, an allergist or dermatologist who works with component-resolved diagnostics can help you decide whether the result changes your treatment plan, including consideration of allergen immunotherapy or biologic medications. If your symptoms are mild and intermittent, a positive result is mainly useful as a record of your sensitization status and a prompt to address mold exposure in your home and workplace.