CD4 and chronic obstructive pulmonary disease: Asthma is characterized by the presence of eosinophils, mast cells, and CD4+ T lymphocytes; whereas COPD is distinguished by the dominance of neutrophils, macrophages and CD8+ T lymphocytes in the respiratory tract (Buist, 2003; Baines et al., 2011; Athanazio, 2012).