CD4 and chronic obstructive pulmonary disease: Because CD4 T cells were consistently positively enriched in E-COPD and end-stage COPD, we then set out to assess functional alternations in CD4 T cells using transcription factor activity analyses (Fig. 2a), gene set over representation analyses (ORA) (Fig. 2b), and gene set variation analysis (GSVA) (Fig. 2c–f).