Previous studies have demonstrated that macrophages are the primary source of cytokines (e.g., interleukin-6 (IL-6), interleukin-10 (IL-10), and interleukin-18 (IL-18)), as well as ferritin, which are closely correlated with disease severity, particularly in ILD/RP-ILD patients (119, 120). This evidence concerns the gene IL18 and interstitial lung disease.