Regulatory T-Cell Distribution within Lung Compartments in COPD

The importance of the adaptive immune response, specifically the role of regulatory T (Treg) cells in controlling the obstruction progression in smokers, has been highlighted. To quantify the adaptive immune cells in different lung compartments, we used lung tissues from 21 never-smokers without lung disease, 22 current and/or ex-smokers without lung disease (NOS) and 13 current and/or ex-smokers with chronic obstructive pulmonary disease (COPD) for histological analysis. We observed increased T, B, IL-17 and BAFF⁺ cells in small and large airways of COPD individuals; however, in the NOS, we only observed increase in T and IL-17⁺ cells only in small airways. A decrease in the density of Treg⁺, TGF-β⁺ and IL-10⁺ in small and large airways was observed only in COPD individuals. In the lymphoid tissues, Treg, T,B-cells and BAFF⁺ cells were also increased in COPD; however, changes in Treg inhibitory associated cytokines were not observed in this compartment. Therefore, our results suggest that difference in Treg⁺ cell distributions in lung compartments and the decrease in TGF-β⁺ and IL-10⁺ cells in the airways may lead to the obstruction in smokers.