In summary, we have shown an increased proportion of three types of cytotoxic cells, namely CD8+ T lymphocytes, NK and NKT-like cells, in the induced sputum of COPD subjects and have demonstrated for the first time that NK and NKT cells are significantly more cytotoxic in COPD subjects than smokers and HNS. This evidence concerns the gene CD8A and chronic obstructive pulmonary disease.