CCL17 and idiopathic interstitial pneumonia: The literature has previously reviewed potential protein biomarkers in the plasma of IPF patients37, broadly categorizing them into three groups: (1) complement and chemoattractant factors (C1R, CCL17, CXCL12, A100A1, ficolin-2), (2) extracellular matrix proteins (actin, cytoplasmic 2, ECM1, and fibronectin), and (3) coagulation factors (antithrombin III, kininogen 1).