What Is Eosinophilic Asthma? Diagnosis, Causes, Complications, and Treatment
There are different types of asthma, including allergic, nonallergic, and exercise-induced. Eosinophilic asthma (also called eos asthma) can happen if you have high levels of eosinophils, a type of white blood cell, in your airways.
Eos asthma is classed as a severe asthma and can result in long-term airway damage.
Eosinophils help your body fight infection. But if too many are present in your airways they can overreact, leading to swelling and other asthma symptoms. The symptoms may be more severe than with other types.
According to the Asthma and Allergy Foundation of America (AAFA) 10 percent of people with asthma in the United States have severe symptoms that are hard to manage. Many of these people, they say, may have eosinophilic asthma.
People with asthma don’t always know if it’s eos asthma or not, as an episode can have the same triggers as other types of asthma, and symptoms can be similar. Your doctor can find out by doing tests.
Asthma is a condition in which airway inflammation makes it hard to breathe. This can result from allergic and nonallergic causes.
“Asthma is characterized by airflow obstruction and limitation of airflow that’s associated with inflammation,” says Michael Wechsler, MD, a codirector of the Cohen Family Asthma Institute at National Jewish Health in Denver. “There’s a subset of asthma patients in whom that inflammation is caused by eosinophils.”
Eosinophils are white blood cells that play an important role in the immune system. They are bigger than most cells and account for less than 5 percent of all your white blood cells.
These cells help your body fight infections, such as bacteria, parasites, and viruses. But, they can also contribute to other diseases, including asthma.
When your immune system fights a pathogen, such as an infection, you’ll notice certain reactions, such as inflammation and swelling. These reactions are a healthy and necessary part of the immune response.
But if your immune system overreacts, symptoms can occur more often and be more severe.
Present throughout the body, normally eosinophils tend to occur in high levels in certain organs, such as the gastrointestinal tract, with lower concentrations in the airways.
High levels of eosinophils in your airways can cause your immune response to be too strong, leading to severe inflammation.
As the Cleveland Clinic website explains, your airways become “clogged” with inflamed eosinophils.
It’s not clear why some people have higher eosinophil levels in their airways, but they may have one or more of the following risk factors.
An allergic reaction
A parasitic disease
A drug reaction
Genetic factors
Stress
Exposure to pollutants
A respiratory infection
Experts believe these factors may trigger an immune response that leads to persistently high levels of eosinophils and chronic inflammation.
Usually, high numbers of eosinophils that occur during an immune response die off and leave the body when they’re no longer needed. For some reason, however, this doesn’t always happen, and levels remain high.
Eos asthma can resemble other types of asthma, but there are also differences.
Age
Eos asthma usually appears in adults rather than children. It commonly starts at 35 to 50 years of age, but it can also affect older people and children.
Allergies
People with eos asthma may not have a history of other allergies, but exposure to environmental substances, such as dust mites, can sometimes trigger it.
Symptoms
In addition to other asthma symptoms, people with eos asthma may also have persistent inflammation in the nose and sinuses and nasal polyps.
Response to Treatment
Doctors categorize severe asthma as either type 2 or non–type 2, depending on how symptoms respond to specific treatments. Eos asthma is a type 2 inflammatory asthma, along with allergic asthma.
Type 2 asthma, such as eos asthma, responds to inhaled corticosteroids and biologic drugs. Non–type 2 asthma may not respond to these drugs.
The symptoms of eosinophilic asthma can resemble those of other asthma types, but there may be additional symptoms.
They include:
Wheezing
Coughing
Shortness of breath or breathing difficulty
Chest tightness
Airflow obstruction, affecting how well the lungs work
People with high eosinophil levels in their airways may also have a risk of developing chronic obstructive pulmonary disease (COPD).
To diagnose eos asthma, a doctor will likely ask about:
Your symptoms
Any history of asthma
Any allergies
Other medical history
They will also carry out a physical examination.
If the doctor suspects eos asthma, they may also do tests to see if you have high levels of eosinophils.
Tests for Eos Asthma
Three tests are used to diagnose eos asthma:
A blood test: A health professional will use a needle to take a small blood sample, usually in a doctor’s office. They’ll then send it to a laboratory for testing. Eosinophil levels of 150 cells per microgram (mcg) or over may be a sign of eos asthma.
A sputum test: You’ll need to cough up a mucus sample, usually in a doctor’s office. Your doctor will send it to a pathologist to examine under a microscope. An eosinophil count of 2 percent or higher in sputum may indicate eos asthma.
A bronchial biopsy: A specialist lung doctor (pulmonologist) will apply local anesthesia and put a narrow tube (bronchoscope) down your throat and into your lungs. The device will collect small samples of tissue and fluid. The doctor will examine this to see if the samples contain eosinophils. You may need to do this in a hospital.
Dr. Wechsler notes: “It’s really important for people with severe asthma to ask, 'What kind of asthma do I have? Do I have eosinophils? What is the subtype of asthma?'” He adds, “New treatments released over the past three years can help with the eosinophilic subtype.”
The right diagnosis will help you get the right treatment.
You can often manage eos asthma with a combination of the usual asthma medications and some special drugs to reduce eosinophil levels in the airways.
Common Asthma Drugs That May Help
Common asthma medications include:
Bronchodilators, which relax and open the airways
Corticosteroids and other anti-inflammatory medications
Options combining both bronchodilators and anti-inflammatory drugs
Some treatments are for long-term use, to prevent attacks. They include inhaled corticosteroids and long-acting beta-agonists.
Others, known as rescue medications, help manage symptoms when they arise. Rescue drugs include short-acting albuterol inhalers and oral corticosteroids.
These drugs help many people with eos asthma but not everyone.
Long-Term Drugs and Biologics for Eos Asthma
If the usual asthma drugs don’t help, your doctor may suggest other long-acting options such as leukotriene modifiers or a biologic drug.
Leukotriene Modifiers
Your body releases leukotrienes as part of the immune response. They can lead to coughing, airway inflammation, and other asthma-like symptoms.
Leukotriene modifiers block the action of leukotrienes and stop these symptoms from happening. They can help with various types of asthma.
Here are some examples:
montelukast (Singulair)
zafirlukast (Accolate)
zileuton (Zyflo)
Biologics
Also known as targeted therapies, biologic drugs reduce inflammation by targeting specific cells and pathways in your body. Doctors will prescribe them alongside other treatments.
Research suggests various biologics can help reduce episodes and improve lung function in people with EOS asthma.
Examples of biologics for eos asthma include:
benralizumab (Fasenra): Delivered as an injection, you can use this drug from the age of 12 years. It reduces inflammation by lowering eosinophil levels.
mepolizumab (Nucala): Also delivered as a shot, this is suitable for those 6 years and older. It reduces eosinophil levels, which decreases inflammation.
reslizumab (Cinqair): This intravenous drug is suitable for people with eos asthma aged 18 or above. It lowers eosinophil levels and reduces inflammation.
dupilumab (Dupixent): Delivered as a shot, this drug helps reduce flares in people aged 6 and over with moderate to severe eos asthma or oral corticosteroid-dependent asthma. It can also help manage severe eczema (atopic dermatitis) and chronic sinusitis with nasal polyposis.
Scientists continue to investigate new options for managing eos and other severe types of asthma.
According to Wechsler, “This treatment doesn’t necessarily eliminate attacks or exacerbations, but in some people it does, and in other people it reduces them dramatically.”
Eosinophilic asthma can lead to complications. It can also occur with or possibly increase the risk of other conditions.
Persistent inflammation with eos asthma may lead to cell changes in the airways, resulting in tissue damage, scarring, and long-term changes to airway structure. This damage may not be reversible.
Other complications or comorbidities include:
Nasal polyps
Persistent sinusitis, rhinitis, or both, known as rhinosinusitis
Aspirin-exacerbated respiratory disease (AERD) due to a higher sensitivity to aspirin
Sensitivity to other nonsteroidal anti-inflammatory drugs (NSAIDs)
Early treatment for eos asthma may reduce the risk of complications.
Eosinophilic asthma can be challenging, but medication and lifestyle choices can help you manage it.
Here are some tips for living well with eos asthma:
Find a specialist doctor you can trust. You may need an allergist, pulmonologist, or both. The American College of Allergy, Asthma & Immunology has an allergist locator on their website to help you find specialist care, and Apfed has one for a range of specialties.
With your doctor, work out a treatment plan and follow it carefully. This includes finding the right medication, using it correctly, and attending follow-up visits.
Learn more about eosinophilic asthma. The more you know about your condition, the more in control and less anxious you'll feel. For instance, you can sign up for a newsletter from dedicated sites such as Apfed.
Keep a log of your symptoms and use it to pinpoint any triggers. Then do your best to avoid them.
Speak with loved ones or seek counseling if living with eos asthma is causing anxiety, depression, or otherwise affecting your mental well-being.
You might also consider joining a clinical trial to find new treatments for eosinophilic asthma. During a clinical trial, you’ll have access to highly specialized professionals. You may also have a chance to try new medications free or charge and before they become widely available.
Eosinophilic asthma, also called eos asthma, is a type of asthma that can happen when you have too many eosinophils, a type of white blood cell, in your airways.
Eosinophils help protect the body from infections and other invaders, but too many can result in an overactive immune response and persistent inflammation.
This form of asthma can be severe, and treatment is essential. Early treatment can prevent long-term damage and complications.
Eos asthma symptoms don’t always respond to the usual asthma treatments. If so, biologic or leukotriene therapy can often help manage this condition.
