CCL4 and chronic obstructive pulmonary disease: Comparing NE-COPD to controls (Fig. 8d), we found that in NE-COPD, activities of TGFβ-TGFβR2, TGFβ-ITGB1, IL1β-IL12RB2, and IL15-IL2RB ligand-receptor pairs were downregulated in CXCR6High CD4 subsets whereas activities of MIF-CD74, MIF-CD44, CCL5-CCR5, CCL4L2-CCR5, and CCL4-CCR5 ligand-receptor pairs were upregulated (Fig. 8d).