IFNG and chronic obstructive pulmonary disease: Similarly, reports of increased expression of CD8+ T cell IFNγ and TNFα in peripheral blood, BAL and bronchial brushings in patients with COPD and the differential expression of these cytokines by these cells between trachea and bronchi also argues for further studies including NK markers to determine if NK and NKT-like cells are also causing cell death in the lungs of COPD patients and if similar biomarkers may predict which smokers will progress to COPD [3,7].