Smoking was found to increase the number of CD8+ T cells and CD8+ NKT-like cells in the BAL of COPD patients with a concurrent reduction of CD4+ cells in the BAL and increase of CD4+ in the blood as previously reported (120, 121), while another study found an increase in iNKT and NKT-like cells in BAL fluid from current smokers but not COPD patients (121). Here, CD4 is linked to chronic obstructive pulmonary disease.