CD8A and chronic obstructive pulmonary disease: Previous studies have shown that the numbers of CD8+ T cells (Cytotoxic T cells, Tc) in the lung parenchyma and small airways are inversely correlated with pulmonary function (O’Shaughnessy et al., 1997; Saetta et al., 1999; Saetta et al., 1998), and depleting these cells may protect against alveolar destruction due to chronic cigarette smoke exposure (Podolin et al., 2013); together, these findings suggest that CD8+ T lymphocytes may play a critical role in COPD pathogenesis.