Perforin expression and cytotoxic activity of sputum CD8+ lymphocytes in patients with COPD.

BACKGROUND

Previous studies have shown that the inflammatory response to cigarette smoking differs between smokers who acquire COPD and those who do not, and the CD8(+) T- lymphocytes have been identified as a key player in this response.

OBJECTIVE

To investigate the cytotoxic activity and perforin expression of CD8(+) lymphocytes in the airway lumen of patients with COPD.

METHODS

Thirty-six male smokers with COPD, 25 male smokers without COPD, and 10 healthy nonsmokers participated in the study. T-lymphocytes of induced sputum samples were labeled with appropriate monoclonal antibodies and measured using flow cytometry. The cytotoxic activity of CD8(+) cells was defined by incubating them with specific target cells (K562).

RESULTS

The percentage and the total number of CD8(+) lymphocytes were significantly higher in COPD smokers compared to non-COPD smokers (p = 0.01 and p = 0.005, respectively) or to healthy nonsmokers (p = 0.02 and p = 0.01, respectively). Perforin expression in CD8(+) cells was significantly higher in smokers with COPD compared to the other two groups (p = 0.001). Increased cytotoxic activity of T cells was also observed in induced sputum of patients with COPD in comparison to the other two groups.

CONCLUSION

CD8(+) cells are not only increased in number in sputum samples of smokers with COPD but are highly activated, expressing high levels of perforin. These findings suggest that CD8(+) T-lymphocytes play a significant role in the inflammatory process of COPD.