To investigate the changes in pro-inflammatory CD4+ T cells in COPD, we measured and analyzed the levels of Th1 cells (CD3+CD8−IFN-γ+), Th2 cells (CD3+CD8−IL-4+), and Th17 cells (CD3+CD8−IL-17A+) in the blood among the three patient groups (Figure 1A). The gene discussed is CD4; the disease is chronic obstructive pulmonary disease.