Circulating leukocyte counts at T0 were higher (p = 0.02) in COPD than in controls, and they did not change at T180 in any group (Figure 1, panel B); likewise, we did not observed any significant change after smoking in circulating neutrophils, lymphocytes (CD3+), CD4+ T cells, CD8+ T, CD19+ B cells or NK populations (data not shown). Here, CD4 is linked to chronic obstructive pulmonary disease.