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 when 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 destroyed, 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 certain genes) that raise your risk for the disease
• —And—
• 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 how severe your symptoms are.

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