CD4 and chronic obstructive pulmonary disease: Combined with our previous findings of an imbalance of pro/anti-inflammatory CD4+ T pools in COPD patients, which revealed increased Th17 cells (only in AECOPD) and Th1 cells and reduced Th2 cells (only in SCOPD) and Th10 cells, as well as an impaired capacity of Tregs, our current research of CD8+ compartment would contribute to the overall interpretation of the true role of T cell pools in COPD.