Autoimmune Pulmonary Alveolar Proteinosis (aPAP)
Autoimmune PAP is the most common form of PAP resulting in the buildup of surfactant in the air sacs of the lungs. There is no cure for this chronic lung condition, but there are treatment options to help manage the symptoms.
Learn About aPAP
This is an ultra-rare lung disease occurring in fewer than 5,000 people in the United States.
Key Facts
- aPAP happens because of the production of antibodies (anti-GM-CSF antibodies) that stop the macrophages (specialized cells) in the lungs from doing their job of removing the extra surfactant from the lungs’ air sacs.
- Surfactant is a naturally occurring substance that helps keep the air sacs of the lungs from collapsing. Buildup of excessive surfactant over time may impair oxygen exchange.
- A simple GM-CSF antibody blood test can help confirm or rule out if you have aPAP.
- Over 90% of people diagnosed with PAP have aPAP.
What Causes aPAP?
Autoimmune PAP is caused by a problem with the immune system. In aPAP, the immune system makes antibodies that block a protein called GM-CSF. This protein normally helps the lungs clear out surfactant, a naturally occurring substance that coats the tiny air sacs in your lungs. When GM-CSF is blocked, surfactant builds up and makes it hard to breathe. The exact reason this occurs in aPAP is not known.
Who is at Risk for aPAP?
Women, men and children of all backgrounds are all equally at risk for autoimmune PAP.
Understanding aPAPs Symptoms
The symptoms of autoimmune PAP are often initially similar to other lung diseases, like asthma and pneumonia. It is important to share all your symptoms with your healthcare provider, including how long you have been experiencing them. More common symptoms may include:
- Shortness of breath
- Fatigue
- Cough (with or without white phlegm)
- Decrease in activity level
Diagnosing aPAP
Your healthcare provider may order several tests to determine if you have autoimmune PAP. Two of the primary tests that help to diagnose aPAP include:
- Chest CT: Imaging of your lungs may show opacities, or hazy areas, with a “crazy paving” pattern in your lungs that may indicate aPAP.
- A simple blood test: aPAP ClearPathTM is a no cost, accessible, accurate blood test that measures the level of the GM-CSF antibodies in your blood to help confirm or rule out if you have aPAP. This blood test can be done through blood drawn from a vein or a finger prick.
Other possible tests that may be ordered include bronchoscopy with bronchoalveolar lavage, a lung biopsy and pulmonary function tests.
Autoimmune PAP (aPAP) is a chronic disease that can be managed but not cured.
Treatment may include the following:
- Whole Lung Lavage (WLL) is a treatment that assists with the removal of the excess surfactant material from the air sacs (alveoli) of the lungs. This washes out the protein substance from the lungs. This invasive procedure is usually reserved for more advanced cases of aPAP.
- GM-CSF Replacement Therapy may involve inhaled GM-CSF therapy using a nebulizer.
- Oxygen therapy may be indicated if determined necessary by your healthcare provider to manage low oxygen levels.
- Lung transplant may be recommended in severe cases.
Management for best health outcomes:
- Find a healthcare provider that specializes in aPAP and follow the treatment plan that is recommended by your healthcare provider.
- Go to all regularly scheduled appointments to make sure that your symptoms are well managed.
- Stay healthy - talk to your healthcare provider about eating healthy, what activity is right for you and staying up to date on all recommended vaccinations to prevent secondary infections that may cause a flare up of your aPAP symptoms.
Find support when living with a chronic lung disease. It is an important part of managing your health. Support groups provide opportunities to learn more about lung disease management and give you the support you need.
- Better Breathers Clubs
Learn ways to cope with lung disease and get support from others living with chronic lung disease. Club meetings are in-person or virtual support groups that give you the tools you need to live the best quality of life you can. - Patient & Caregiver Network
A nationwide, online support program that provides direct access to education, support and connection to others living with lung disease. - Living with Lung Disease
Connect with others, share experiences and learn from friends in this free online forum for people facing lung disease. Our Living with Lung Disease virtual support group can help build your support network and give you a place to chat with peers about how your lung disease is affecting you. - Lung HelpLine
Open seven days a week and staffed by experienced registered nurses, respiratory therapists and certified tobacco treatment specialists to answer your call. We are here to provide you with the support you need and the answers you are looking for. - PAP Foundation
This non-profit patient advocacy organization is dedicated to those impacted by PAP.
Page last updated: August 26, 2025
