Effector T-cell dysfunction in COPD has been related to the accumulation of functionally suppressive Tregs, a subset of CD4+ T cells which regulate immune response and establish peripheral tolerance, but which also play a decisive role in controlling effector T-cell function through the secretion of inhibitory cytokines such as TGF-β, IL-35, and IL-10 [89]. The gene discussed is IL10; the disease is chronic obstructive pulmonary disease.