CCR7 and chronic obstructive pulmonary disease: In the present study, to further investigate whether the increase in the number of mature DCs in the airways of patients with COPD may be explained by an increase in the numbers of CCR7+ cells, CCR7+ expression in the human lung at the mRNA level was determined, and the CCR7+ expression levels among non-smokers, smokers without COPD and patients with COPD were compared.