The proportion of CCR6+ CXCR3+ CD4+ T cells within the blood of our IPF cohort (mean, 0.22 ± 0.25%) was significantly decreased when compared to the proportion of lung and LLN CCR6+ CXCR3+ CD4+ T cells (mean, 3.43 ± 2.27%; and mean, 3.18 ± 1.00%; p = 0.0011, respectively) (Figures 2B,F). This evidence concerns the gene CD4 and idiopathic pulmonary fibrosis.