CD8A and chronic obstructive pulmonary disease: Significantly more CD8+ T-lymphocytes from both healthy smokers (52.3%, 27.2–72.8; p<0.001) and current smokers with COPD (34.3%, 13.8–56.2; p<0.001) were activated ex vivo compared to healthy non-smokers (5.1%, 2.5–13.3) (Figure 2A).