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What Causes Sarcoidosis?

The cause of sarcoidosis isn't known. More than one factor may play a role in causing the disease.

Some researchers think that sarcoidosis develops if your immune system responds to a trigger, such as bacteria, viruses, dust, or chemicals.

Normally, your immune system defends your body against foreign or harmful substances. For example, it sends special cells to protect organs that are in danger.

These cells release chemicals that recruit other cells to isolate and destroy the harmful substance. Inflammation occurs during this process. Once the harmful substance is gone, the cells and the inflammation go away.

In people who have sarcoidosis, the inflammation doesn't go away. Instead, some of the immune system cells cluster to form lumps called granulomas in various organs in your body.

Genetics also may play a role in sarcoidosis. Researchers believe that sarcoidosis occurs if:

  • You have a certain gene or genes that raise your risk for the disease


  • You're exposed to something that triggers your immune system

Triggers may vary depending on your genetic makeup. Certain genes may influence which organs are affected and the severity of your symptoms.

Researchers continue to try to pinpoint the genes that are linked to sarcoidosis.

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June 14, 2013 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.