Eosinophilic Lung Diseases

Reviewed by Rafeul Alam, MD, PhD

Eosinophilic lung diseases are a category of lung problems. They are characterized by having an increased number of eosinophils (white blood cells) in the lungs. These white blood cells are part of the immune system. They fight off allergic or chemical reactions and certain infections.

 

Eosinophilic Pneumonia

Eosinophilic pneumonia describes a category of pneumonias that feature increased numbers of eosinophils in the lung tissue. Pneumonia is an inflammatory condition of the lungs, involving the air sacs. When the lungs are inflamed, they become swollen. This can result in low oxygen in the bloodstream.

 

Acute Eosinophilic Pneumonia

Acute eosinophilic pneumonia is a more sudden and faster progression of this type of pneumonia. It can be dangerous. It can progress to respiratory failure and require hospitalization. Symptoms include wheezing, chest tightness, cough, chest pain, increased phlegm (mucus), shortness of breath and rapid breathing. It may involve bloody mucus, fever, muscle aches, decreased oxygenation, and even respiratory failure.  Acute eosinophilic pneumonia results from excessive activation of type-2 immune cells and production of type-2 cytokines such as interleukin-5. This results in excessive influx of eosinophils in the lung. 

 

Chronic Eosinophilic Pneumonia

Chronic eosinophilic pneumonia describes eosinophilic pneumonia that typically lasts for more than one month. The symptoms of chronic eosinophilic pneumonia are slower and more low grade than the acute type. People may have a lingering illness and generally feel unwell. They may also have a cough; progressive shortness of breath; persistent asthma-like symptoms, such as chest tightness and wheezing; or weight loss. Symptoms can be similar to acute eosinophilic pneumonia but do not progress as quickly. Chronic eosinophilic pneumonia can occur with blood cancer, autoimmune disease, fungal infection or parasitic infection.  However, in most cases the cause is excessive activation of type-2 immune cells and production of type-2 cytokines such as interleukin-5. This results in excessive influx of eosinophils in the lung. 

 

Eosinophilic Pneumonia Diagnosis

If eosinophilic pneumonia is suspected, your doctor may order imaging tests, such as a CT scan of the chest or a chest X-ray. He or she will order blood tests to determine the level of eosinophils circulating in the blood. Other blood tests may include other markers of inflammation or underlying disease in the blood. In order to determine if a pneumonia fits in the category of eosinophilic pneumonia, a biopsy may be done. This will help confirm that there is an increase in eosinophil number in the lung tissue.

 

Eosinophilic Pneumonia Treatment

Treatment of acute eosinophilic pneumonia may require hospitalization. It may be necessary to support the person with assistance from a breathing machine. Treatment with intravenous (IV) steroids or other medications that suppress the immune system. This may help stop or decrease the inflammation and prevent respiratory failure. Biologics targeting interleukin-5 (Mepolizumab, Reslizumab) or interleukin-5 receptor on eosinophils (Benralizumab) are very effective in treating eosinophilic inflammation.  These injectable biologics can be used to treat eosinophilic pneumonia.  Finding and treating underlying causes such as malignancy (cancerous cells that can spread throughout the body), autoimmune disease and infection also is important.

 

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