CD27 and chronic obstructive pulmonary disease: We found that the lung tissue of patients with COPD had a greater proportion of terminally differentiated CD8+CD28-CD27- cytotoxic cells, than healthy lung tissue of donors (Table 2, Figures 4B, C) (p= 0.036; 98.9% [65.1–100] vs. 87.5% [47.3–99.9], respectively) and, consequently a lower proportion of partly differentiated CD8+CD28-CD27+ cells (P = 0.015: 0.5% [65.1–100] vs. 12.5% [0–52.5], respectively).