However, our results are in contrast with the findings of Barcelò et al., showing that no differences in CD4+CD25+ Tregs from peripheral blood were detected among COPD, healthy smokers and controls and with the results of Vargas-Rojas et al. describing increased levels of Treg cells present in COPD and smokers subjects compared to healthy ones [6, 30]. This evidence concerns the gene CD4 and chronic obstructive pulmonary disease.