CD4 and pulmonary fibrosis: The results showed that the proportion of Th9 cells in CD4+ T lymphocytes in the PBMC of patients with IPF was significantly higher than that in healthy controls (Figure 1B) and positively correlated with CT score (Figure 1C), indicating that the increase of Th9 cells is positively correlated with the severity of pulmonary fibrosis in patients with IPF.