The percentage positive area of inflammatory cells in bronchial biopsies (CD3, CD4, CD8, CD20, neutrophils, macrophages, eosinophils and mast cells) did not differ between COPD (GOLD I-III), symptomatic smokers (GOLD 0) and asymptomatic smokers (table 2). Here, CD4 is linked to chronic obstructive pulmonary disease.