CCR4 and chronic obstructive pulmonary disease: Immunofluorescent analysis of airway mucosal biopsies in patients with asthma showed that most T cells co-express IL-4 and CCR4, but, in contrast, T cells in airways of patients with COPD and pulmonary sarcoidosis produce IFN-γ and express high levels of CXCR3, while lacking CCR4 expression [26].