Idiopathic pulmonary fibrosis (IPF) is the most common form of chronic idiopathic diffuse interstitial lung disease (DILD) in adults. It is a fibroproliferative, irreversible disease of unknown cause, usually progressive, occurring mainly from the age of 60 and limited to the lungs. IPF is a serious disease with a median survival rate at diagnosis of 3 years.

The aim of the study is to set up a biocollection of serum from patients in a context of idiopathic DILD and a possible or confirmed diagnosis of common interstitial lung disease by chest CT.

Patients will be recruited at the consultations of the Rennes Rare Lung Disease Competence Centre. These will be patients in stable condition or in acute exacerbation of IPF.

This study will initially focus on circulating serum CD163 markers, but a broader proteomics approach could be considered in a second phase to look for other markers of lung diseases.

Inclusion Criteria:

• Patients seen on an outpatient basis and in stable or acute condition
• Patient over 18 years of age.
• The inclusion criteria will be those edited by the American Thoracic Society (ATS) and the European Respiratory Society (ERS) to diagnosis IPF

Exclusion Criteria:

• Patients who are unable or unwilling to sign the consent.

Patients will be recruited at the consultations of the Rennes Rare Lung Disease Competence Centre. These will be patients in stable condition or in acute exacerbation of IPF.